Production of ethylene with nanowire catalysts

ABSTRACT

Nanowires useful as heterogeneous catalysts are provided. The nanowires catalysts are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to ethylene. Related methods for use and manufacture of the same are also disclosed.

The Sequence Listing associated with this application is provided in text format in lieu of a paper copy, and is hereby incorporated by reference into the specification. The name of the text file containing the Sequence Listing is 620058_418C3_SEQUENCE_Listings. The text file is 9.5 FB, was created on Sep. 13, 2019, and is being submitted electronically via EFTS-Web.

BACKGROUND Technical Field

This invention is generally related to novel nanowire catalysts and, more specifically, to nanowires useful as heterogeneous catalysts in a variety of catalytic reactions, such as the oxidative coupling of methane to ethylene.

Description of the Related Art

Catalysis is the process in which the rate of a chemical reaction is either increased or decreased by means of a catalyst. Positive catalysts increase the speed of a chemical reaction, while negative catalysts slow it down. Substances that increase the activity of a catalyst are referred to as promoters or activators, and substances that deactivate a catalyst are referred to as catalytic poisons or deactivators. Unlike other reagents, a catalyst is not consumed by the chemical reaction, but instead participates in multiple chemical transformations. In the case of positive catalysts, the catalytic reaction generally has a lower rate-limiting free energy change to the transition state than the corresponding uncatalyzed reaction, resulting in an increased reaction rate at the same temperature. Thus, at a given temperature, a positive catalyst tends to increase the yield of desired product while decreasing the yield of undesired side products. Although catalysts are not consumed by the reaction itself, they may be inhibited, deactivated or destroyed by secondary processes, resulting in loss of catalytic activity.

Catalysts are generally characterized as either heterogeneous or homogeneous. Heterogeneous catalysts exist in a different phase than the reactants (e.g. a solid metal catalyst and gas phase reactants), and the catalytic reaction generally occurs on the surface of the heterogeneous catalyst. Thus, for the catalytic reaction to occur, the reactants must diffuse to and/or adsorb onto the catalyst surface. This transport and adsorption of reactants is often the rate limiting step in a heterogeneous catalysis reaction. Heterogeneous catalysts are also generally easily separable from the reaction mixture by common techniques such as filtration or distillation.

In contrast to a heterogeneous catalyst, a homogenous catalyst exists in the same phase as the reactants (e.g., a soluble organometallic catalyst and solvent-dissolved reactants). Accordingly, reactions catalyzed by a homogeneous catalyst are controlled by different kinetics than a heterogeneously catalyzed reaction. In addition, homogeneous catalysts can be difficult to separate from the reaction mixture.

While catalysis is involved in any number of technologies, one particular area of importance is the petrochemical industry. At the foundation of the modern petrochemical industry is the energy-intensive endothermic steam cracking of crude oil. Cracking is used to produce nearly all the fundamental chemical intermediates in use today. The amount of oil used for cracking and the volume of green house gases (GHG) emitted in the process are quite large: cracking consumes nearly 10% of the total oil extracted globally and produces 200M metric tons of CO₂ equivalent every year (Ren, T, Patel, M. Res. Conserv. Recycl. 53:513, 2009). There remains a significant need in this field for new technology directed to the conversion of unreactive petrochemical feedstocks (e.g. paraffins, methane, ethane, etc.) into reactive chemical intermediates (e.g. olefins), particularly with regard to highly selective heterogeneous catalysts for the direct oxidation of hydrocarbons.

While there are multistep paths to convert methane to certain specific chemicals using first; high temperature steam reforming to syngas (a mixture of H₂ and CO), followed by stochiometry adjustment and conversion to either methanol or, via the Fischer-Tropsch (F-T) synthesis, to liquid hydrocarbon fuels such as diesel or gasoline, this does not allow for the formation of certain high value chemical intermediates. This multi-step indirect method also requires a large capital investment in facilities and is expensive to operate, in part due to the energy intensive endothermic reforming step. (For instance, in methane reforming, nearly 40% of methane is consumed as fuel for the reaction.) It is also inefficient in that a substantial part of the carbon fed into the process ends up as the GHG CO₂, both directly from the reaction and indirectly by burning fossil fuels to heat the reaction. Thus, to better exploit the natural gas resource, direct methods that are more efficient, economical and environmentally responsible are required.

One of the reactions for direct natural gas activation and its conversion into a useful high value chemical, is the oxidative coupling of methane (“OHM”) to ethylene: 2UCH₄+O₂→C₂H₄+2H₂O. See, e.g., Hang, Q., Journal of Natural Gas Them., 12:81, 2003; Oath, G. “Hydrocarbon Chemistry”, Ed. 2, John Wiley & Sons (2003). This reaction is exothermic (ΔH=−67 kcals/mole) and has only been shown to occur at very high temperatures (>700° C.). Although the detailed reaction mechanism is not fully characterized, experimental evidence suggests that free radical chemistry is involved. (Lunsford, J. Them. Soc., Chem. Comm., 1991; H. Lunsford, Angew. Chem.. Int. Ed. Engl., 34:970, 1995). In the reaction, methane (CH₄) is activated on the catalyst surface, forming methyl radicals which then couple in the gas phase to form ethane (C₂H₆), followed by dehydrogenation to ethylene (C₂H₄). Several catalysts have shown activity for OCM, including various forms of iron oxide, V₂O₅, MoO₃, Co₃O₄, Pt-Rh, Li/ZrO₂, Ag-Au, Au/Co₃O₄, Co/Mn, CeO₂, MgO, La₂O₃, Mn₃O₄, Na₂WO₄, MnO, ZnO, and combinations thereof, on various supports. A number of doping elements have also proven to be useful in combination with the above catalysts.

Since the OCM reaction was first reported over thirty years ago, it has been the target of intense scientific and commercial interest, but the fundamental limitations of the conventional approach to C—H bond activation appear to limit the yield of this attractive reaction. Specifically, numerous publications from industrial and academic labs have consistently demonstrated characteristic performance of high selectivity at low conversion of methane, or low selectivity at high conversion (J. A. Labinger, Cat. Left., 1:371, 1988). Limited by this conversion/selectivity threshold, no OCM catalyst has been able to exceed 20-25% combined C2 yield (i.e. ethane and ethylene), and all such yields are reported at extremely high temperatures (>800C). This lack of progress with conventional heterogeneous catalysts and reactors during the last third of a century suggests that conventional approaches have reached the limit of their performance.

In this regard, it is believed that the low yield of desired products (i.e. C₂H₄ and C₂H₆) is caused by the unique homogeneous/heterogeneous nature of the reaction. Specifically, due to the high reaction temperature, a majority of methyl radicals escape the catalyst surface and enter the gas phase. There, in the presence of oxygen and hydrogen, multiple side reactions are known to take place (J. A. Labinger, Cat. Lett., 1:371, 1988). The non-selective over-oxidation of hydrocarbons to CO and CO₂ (e.g., complete oxidation) is the principal competing fast side reaction. Other undesirable products (e.g. methanol, formaldehyde) have also been observed and rapidly react to form CO and CO₂.

In order to dramatically increase the yield of OCM, a catalyst optimized for the activation of the C—H bond of methane at lower temperatures (e.g. 500-900° C.) is required. While the above discussion has focused on the OCM reaction, numerous other catalytic reactions (as discussed in greater detail below) would significantly benefit from catalytic optimization. Accordingly, there remains a need in the art for improved catalysts and, more specifically, a need for novel approaches to catalyst design for improving the yield of, for example, the OCM reaction and other catalyzed reactions. The present invention fulfills these needs and provides further related advantages.

BRIEF SUMMARY

In brief, nanowires and related methods are disclosed. In one embodiment, the disclosure provides a catalyst comprising an inorganic catalytic polycrystalline nanowire, the nanowire having a ratio of effective length to actual length of less than one and an aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the nanowire comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof.

In another embodiment, the disclosure provides a catalytic material comprising a plurality of inorganic catalytic polycrystalline nanowires, the plurality of nanowires having a ratio of average effective length to average actual length of less than one and an average aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the plurality of nanowires comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof.

In yet another embodiment, a method for preparing inorganic catalytic polycrystalline nanowires is provided, the nanowires each having a ratio of effective length to actual length of less than one and an aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the nanowires each comprise one or more elements selected from Groups 1 through 7, lanthanides, actinides or combinations thereof. The method comprises:

admixing (A) with a mixture comprising (B) and (C);

admixing (B) with a mixture comprising (A) and (C); or

admixing (C) with a mixture comprising (A) and (B) to obtain a mixture comprising (A), (B) and (C), wherein (A), (B), and (C) comprise, respectively:

(A) a biological template;

(B) one or more salts comprising one or more metal elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof; and

(C) one or more anion precursors.

In another embodiment, a process for the preparation of ethylene from methane comprising contacting a mixture comprising oxygen and methane at a temperature below 900° C. with a catalyst comprising one or more inorganic catalytic nanowires is provided.

In yet another embodiment, the present disclosure provides for the use of a catalytic nanowire in a catalytic reaction. The nanowire may have any composition or morphology, for example the nanowire may comprise one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof, and the nanowire may optionally be a polycrystalline nanowire, the nanowire having a ratio of effective length to actual length of less than one and an aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV.

In another embodiment, the present disclosure provides a method for preparing a downstream product of ethylene, the method comprising converting ethylene to a downstream product of ethylene, wherein the ethylene has been prepared via a reaction employing a catalytic nanowire. In certain embodiments, the nanowire comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof, and the nanowire may optionally be a polycrystalline nanowire, the nanowire having a ratio of effective length to actual length of less than one and an aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV.

In another embodiment, the disclosure provides an inorganic nanowire comprising one or more metal elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof, and a dopant comprising a metal element, a semi-metal element, a non-metal element or combinations thereof.

In another embodiment, the disclosure provides a method for preparing a metal oxide nanowire comprising a plurality of metal oxides (M_(x)O_(y)), the method comprising:

a) providing a solution comprising a plurality of biological templates;

(b) introducing at least one metal ion and at least one anion to the solution under conditions and for a time sufficient to allow for nucleation and growth of a nanowire comprising a plurality of metal salts (M_(m)X_(n)Z_(p)) on the template; and

(c) converting the nanowire (M_(m)X_(n)Z_(p)) to a metal oxide nanowire comprising a plurality of metal oxides (M_(x)O_(y)),

wherein:

M is, at each occurrence, independently a metal element from any of Groups 1 through 7, lanthanides or actinides;

X is, at each occurrence, independently hydroxides, carbonates, bicarbonates, phosphates, hydrogenphosphates, dihydrogenphosphates, sulfates, nitrates or oxalates;

Z is O;

n, m, x and y are each independently a number from 1 to 100; and

p is a number from 0 to 100.

In another embodiment, the disclosure provides a method for preparing a metal oxide nanowire, the method comprising:

(a) providing a solution comprising a plurality of biological templates; and

(b) introducing a compound comprising a metal to the solution under conditions and for a time sufficient to allow for nucleation and growth of a nanowire (M_(m)Y_(n)) on the template;

wherein:

M is a metal element from any of Groups 1 through 7, lanthanides or actinides;

Y is O,

n and m are each independently a number from 1 to 100.

In another embodiment, the disclosure provides a method for preparing metal oxide nanowires in a core/shell structure, the method comprising:

(a) providing a solution comprising a plurality of biological templates;

(b) introducing a first metal ion and a first anion to the solution under conditions and for a time sufficient to allow for nucleation and growth of a first nanowire (M1_(m1)X1_(n1)Z_(p1)) on the template; and

(c) introducing a second metal ion and optionally a second anion to the solution under conditions and for a time sufficient to allow for nucleation and growth of a second nanowire (M2_(m2)X2_(n2)Z_(p2)) on the first nanowire (M1_(m1)X1_(n1)Z_(p1)),

(d) converting the first nanowire (M1_(m1)X1_(n1)Z_(p1)) and the second nanowire (M2_(m2)X2_(n2)Z_(p2)) to respective metal oxide nanowires (M1_(x1)O_(y1)) and (M2_(x2)O_(y2)).

wherein:

M1 and M2 are the same or different and independently selected from a metal element from any of Groups 1through 7, lanthanides or actinides;

X1 and X2 are the same or different and independently hydroxides, carbonates, bicarbonates, phosphates, hydrogenphosphates, dihydrogenphosphates, sulfates, nitrates or oxalates;

Z is O;

n1, m1, n2, m2, x1, y1, x2 and y2 are each independently a number from 1 to 100; and

p1 and p2 are each independently a number from 0 to 100.

In yet another embodiment, the present disclosure provides a method for the preparation of a downstream product of ethylene, the method comprising converting methane into ethylene in the presence of a catalytic nanowire and further oligomerizing the ethylene to prepare a downstream product of ethylene. In certain embodiments, the nanowire comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof, and the nanowire may optionally be a polycrystalline nanowire, the nanowire having a ratio of effective length to actual length of less than one and an aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV.

These and other aspects of the invention will be apparent upon reference to the following detailed description. To this end, various references are set forth herein which describe in more detail certain background information, procedures, compounds and/or compositions, and are each hereby incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, the sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not intended to convey any information regarding the actual shape of the particular elements, and have been selected solely for ease of recognition in the drawings.

FIG. 1 schematically depicts a first part of an OCM reaction at the surface of a metal oxide catalyst.

FIG. 2 shows a high throughput work flow for synthetically generating and testing libraries of nanowires.

FIGS. 3A and 3B illustrate a nanowire in one embodiment.

FIGS. 4A and 4B illustrate a nanowire in a different embodiment.

FIGS. 5A and 5B illustrate a plurality of nanowires.

FIG. 6 illustrates a filamentous bacteriophage.

FIG. 7 is a flow chart of a nucleation process for forming a metal oxide nanowire.

FIG. 8 is a flow chart of a sequential nucleation process for forming a nanowire in a core/shell configuration.

FIG. 9 schematically depicts a carbon dioxide reforming reaction on a catalytic surface.

FIG. 10 is a flow chart for data collection and processing in evaluating catalytic performance.

FIG. 11 illustrates a number of downstream products of ethylene.

FIG. 12 depicts a representative process for preparing a lithium doped MgO nanowire.

FIG. 13 presents the X-ray diffraction patterns of Mg(OH)₂ nanowires and MgO nanowires.

FIG. 14 shows a number of MgO nanowires each synthesized in the presence of a different phage sequence.

FIG. 15 depicts a representative process for growing a core/shell structure of ZrO₂/ La₂O₃ nanowires with Strontium dopant.

FIG. 16 is a gas chromatograph showing the formation of OCM products at 700° C. when passed over a Sr doped La₂O₃ nanowire.

FIGS. 17A-17C are graphs showing methane conversion, C2 selectivity, and C2 yield, in an OCM reaction catalyzed by Sr doped La₂O₃ nanowires vs. the corresponding bulk material in the same reaction temperature range.

FIGS. 18A-18B are graphs showing the comparative results of C2 selectivities in an OCM reaction catalyzed by Sr doped La₂O₃ nanowire catalysts prepared by different synthetic conditions.

FIG. 19 is a graph comparing ethane and propane conversions in ODH reactions catalyzed by either Li doped MgO phage-based nanowires or Li doped MgO bulk catalyst.

FIG. 20 is a TEM image showing La₂O₃ nanowires prepared under non-template-directed conditions.

FIG. 21 depicts OCM and ethylene oligomerization modules.

FIG. 22 shows methane conversion, C2 selectivity and C2 yield in a reaction catalyzed by a representative nanowire at a CH₄/O₂ ratio of 4.

FIG. 23 shows methane conversion, C2 selectivity and C2 yield in a reaction catalyzed by a representative nanowire at a CH₄/O₂ ratio of 5.5.

FIG. 24 is a graph showing methane conversion, C2 selectivity and C2 yield in a reaction catalyzed by Mg/Na doped La₂O₃ nanowires.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments. However, one skilled in the art will understand that the invention may be practiced without these details. In other instances, well-known structures have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments. Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is, as “including, but not limited to.” Further, headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed invention.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Also, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

As discussed above, heterogeneous catalysis takes place between several phases. Generally, the catalyst is a solid, the reactants are gases or liquids and the products are gases or liquids. Thus, a heterogeneous catalyst provides a surface that has multiple active sites for adsorption of one more gas or liquid reactants. Once adsorbed, certain bonds within the reactant molecules are weakened and dissociate, creating reactive fragments of the reactants, e.g., in free radical forms. One or more products are generated as new bonds between the resulting reactive fragments form, in part, due to their proximity to each other on the catalytic surface.

As an example, FIG. 1 shows schematically the first part of an OCM reaction that takes place on the surface of a metal oxide catalyst 10 which is followed by methyl radical coupling in the gas phase. A crystal lattice structure of metal atoms 14 and oxygen atoms 20 are shown, with an optional dopant 24 incorporated into the lattice structure. In this reaction, a methane molecule 28 comes into contact with an active site (e.g., surface oxygen 30) and becomes activated when a hydrogen atom 34 dissociates from the methane molecule 28. As a result, a methyl radical 40 is generated on or near the catalytic surface. Two methyl radicals thus generated can couple in the gas phase to create ethane and/or ethylene, which are collectively referred to as the “C2” coupling products.

It is generally recognized that the catalytic properties of a catalyst strongly correlate to its surface morphology. Typically, the surface morphology can be defined by geometric parameters such as: (1) the number of surface atoms (e.g., the surface oxygen of FIG. 1) that coordinate to the reactant; and (2) the degree of coordinative unsaturation of the surface atoms, which is the coordination number of the surface atoms with their neighboring atoms. For example, the reactivity of a surface atom decreases with decreasing coordinative unsaturation. For example, for the dense surfaces of a face-centered crystal, a surface atom with 9 surface atom neighbors will have a different reactivity than one with 8 neighbors. Additional surface characteristics that may contribute to the catalytic properties include, for example, crystal dimensions, lattice distortion, surface reconstructions, defects, grain boundaries, and the like. See, e.g., Van Santen R. A. et al New Trends in Materials Chemistry 345-363 (1997).

Catalysts in nano-size dimensions have substantially increased surface areas compared to their counterpart bulk materials. The catalytic properties are expected to be enhanced as more surface active sites are exposed to the reactants. Typically in traditional preparations, a top-down approach (e.g., milling) is adopted to reduce the size of the bulk material. However, the surface morphologies of such catalysts remain largely the same as those of the parent bulk material.

Various embodiments described herein are directed to nanowires with controllable or tunable surface morphologies. In particular, nanowires synthesized by a “bottom up” approach, by which inorganic polycrystalline nanowires are nucleated from solution phase in the presence of a template, e.g., a linear or anisotropic shaped biological template. By varying the synthetic conditions, nanowires having different compositions and/or different surface morphologies are generated.

In contrast to a bulk catalyst of a given elemental composition, which is likely to have a particular corresponding surface morphology, diverse nanowires with different surface morphologies can be generated despite having the same elemental composition. In this way, morphologically diverse nanowires can be created and screened according to their catalytic activity and performance parameters in any given catalytic reaction. Advantageously, the nanowires disclosed herein and methods of producing the same have general applicability to a wide variety of heterogeneous catalyses, including without limitation: oxidative coupling of methane (e.g., FIG. 1), oxidative dehydrogenation of alkanes to their corresponding alkenes, selective oxidation of alkanes to alkenes and alkynes, oxidation of carbon monoxide, dry reforming of methane, selective oxidation of aromatics, Fischer-Tropsch reaction, hydrocarbon cracking and the like.

FIG. 2 schematically shows a high throughput work flow for synthetically generating libraries of morphologically or compositionally diverse nanowires and screening for their catalytic properties. An initial phase of the work flow involves a primary screening, which is designed to broadly and efficiently screen a large and diverse set of nanowires that logically could perform the desired catalytic transformation. For example, certain doped bulk metal oxides (e.g., Li/MgO and Sr/La₂O₃) are known catalysts for the OCM reaction. Therefore, nanowires of various metal oxide compositions and/or surface morphologies can be prepared and evaluated for their catalytic performances in an OCM reaction.

More specifically, the work flow 100 begins with designing synthetic experiments based on solution phase template formations (block 110). The synthesis, subsequent treatments and screenings can be manual or automated. As will be discussed in more detail herein, by varying the synthetic conditions, nanowires can be prepared with various surface morphologies and/or compositions in respective microwells (block 114). The nanowires are subsequently calcined and then optionally doped (block 120). Optionally, the doped and calcined nanowires are further mixed with a catalyst support (block 122). Beyond the optional support step, all subsequent steps are carried out in a “wafer” format, in which nanowire catalysts are deposited in a quartz wafer that has been etched to create an ordered array of microwells. Each microwell is a self-contained reactor, in which independently variable processing conditions can be designed to include, without limitation, respective choices of elemental compositions, catalyst support, reaction precursors, templates, reaction durations, pH values, temperatures, ratio between reactants, gas flows, and calcining conditions (block 124). Due to design contrasts of some wafers, in some embodiments calcining and other temperature variables are identical in all microwells. A wafer map 130 can be created to correlate the processing conditions to the nanowire in each microwell. A library of diverse nanowires can be generated in which each library member corresponds to a particular set of processing conditions and corresponding compositional and/or morphological characteristics.

Nanowires obtained under various synthetic conditions are thereafter deposited in respective microwells of a wafer (140) for evaluating their respective catalytic properties in a given reaction (blocks 132 and 134). The catalytic performance of each library member can be screened serially by several known primary screening technologies, including scanning mass spectroscopy (SMS) (Symyx Technologies Inc., Santa Clara, Calif.). The screening process is fully automated, and the SMS tool can determine if a nanowire is catalytically active or not, as well as its relative strength as a catalyst at a particular temperature. Typically, the wafer is placed on a motion control stage capable of positioning a single well below a probe that flows the feed of the starting material over the nanowire surface and removes reaction products to a mass spectrometer and/or other detector technologies (blocks 134 and 140). The individual nanowire is heated to a preset reaction temperature, e.g., using a CO₂ IR laser from the backside of the quartz wafer and an IR camera to monitor temperature and a preset mixture of reactant gases. The SMS tool collects data with regard to the consumption of the reactant(s) and the generation of the product(s) of the catalytic reaction in each well (block 144), and at each temperature and flow rate.

The SMS data obtained as described above provide information on relative catalytic properties among all the library members (block 150). In order to obtain more quantitative data on the catalytic properties of the nanowires, possible hits that meet certain criteria are subjected to a secondary screening (block 154). Typically, secondary screening technologies include a single, or alternatively multiple channel fixed-bed or fluidized bed reactors (as described in more detail herein). In parallel reactor systems or multi-channel fixed-bed reactor system, a single feed system supplies reactants to a set of flow restrictors. The flow restrictors divide the flows evenly among parallel reactors. Care is taken to achieve uniform reaction temperature between the reactors such that the various nanowires can be differentiated solely based on their catalytic performances. The secondary screening allows for accurate determination of catalytic properties such as selectivity, yield and conversion.(block 160). These results serve as a feedback for designing further nanowire libraries. Additional description of SMS tools in a combinatorial approach for discovering catalysts can be found in, e.g., Bergh, S. et al. Topics in Catalysts 23:1-4, 2003.

Thus, in accordance with various embodiments described herein, compositional and morphologically diverse nanowires can be rationally synthesized to meet catalytic performance criteria. These and other aspects of the present disclosure are described in more detail below.

Definitions

As used herein, and unless the context dictates otherwise, the following terms have the meanings as specified below.

“Catalyst” means a substance which alters the rate of a chemical reaction. A catalyst may either increase the chemical reaction rate (i.e. a “positive catalyst”) or decrease the reaction rate (i.e. a “negative catalyst”). Catalysts participate in a reaction in a cyclic fashion such that the catalyst is cyclically regenerated. “Catalytic” means having the properties of a catalyst.

“Nanoparticle” means a particle having at least one diameter on the order of nanometers (e.g. between about 1 and 100 nanometers).

“Nanowire” means a nanowire structure having at least one diameter on the order of nanometers (e.g. between about 1 and 100 nanometers) and an aspect ratio greater than 10:1. The “aspect ratio” of a nanowire is the ratio of the actual length (L) of the nanowire to the diameter (D) of the nanowire. Aspect ratio is expressed as L: D.

“Polycrystalline nanowire” means a nanowire having multiple crystal domains. Polycrystalline nanowires generally have different morphologies (e.g. bent vs. straight) as compared to the corresponding “single-crystalline” nanowires.

“Effective length” of a nanowire means the shortest distance between the two distal ends of a nanowire as measured by transmission electron microscopy (TEM) in bright field mode at 5 keV. “Average effective length” refers to the average of the effective lengths of individual nanowires within a plurality of nanowires.

“Actual length” of a nanowire means the distance between the two distal ends of a nanowire as traced through the backbone of the nanowire as measured by TEM in bright field mode at 5 keV. “Average actual length” refers to the average of the actual lengths of individual nanowires within a plurality of nanowires.

The “diameter” of a nanowire is measured in an axis perpendicular to the axis of the nanowire's actual length (i.e. perpendicular to the nanowires backbone). The diameter of a nanowire will vary from narrow to wide as measured at different points along the nanowire backbone. As used herein, the diameter of a nanowire is the most prevalent (i.e. the mode) diameter.

The “ratio of effective length to actual length” is determined by dividing the effective length by the actual length. A nanowire having a “bent morphology” will have a ratio of effective length to actual length of less than one as described in more detail herein. A straight nanowire will have a ratio of effective length to actual length equal to one as described in more detail herein.

“Inorganic” means a substance comprising a metal element. Typically, an inorganic can be one or more metals in its elemental state, or more preferably, a compound formed by a metal ion (M^(n+), wherein n 1, 2, 3, 4, 5, 6 or 7) and an anion (X^(m−), m is 1, 2, 3 or 4) which balance and neutralize the positive charges of the metal ion through electrostatic interactions. Non-limiting examples of inorganic compounds include oxides, hydroxides, halides, nitrates, sulfates, carbonates, acetates, oxalates, and combinations thereof, of metal elements. Other non-limiting examples of inorganic compounds include Li₂CO₃, LiOH, Li₂O, LiCl, LiBr, Lil, Li₂C₂O₄, Li₂SO₄, Na₂CO₃, NaOH, Na₂O, NaCl, NaBr, NaI, Na₂C₂O₄, Na₂SO₄, K₂CO₃, KOH, K₂O, KCl, KBr, KI, K₂C₂O₄, K₂SO₄, CsCO₃, CsOH, Cs₂O, CsCl, CsBr, CsI, CsC₂O₄, CsSO₄, Be(OH)₂, BeCO₃, BeO, BeCl₂, BeBr₂, BeI₂, BeC₂O₄, BeSO₄, Mg(OH)₂, MgCO₃, MgO, MgCl₂, MgBr₂, MgI₂, MgC₂O₄, MgSO₄, Ca(OH)₂, CaO, CaCl₂, CaBr₂, CaI₂, Ca(OH)₂, CaC₂O₄, CaSO₄, Y₂O₃, Y₂(CO3)₃, Y(OH)₃, YCl₃, YBr₃, YI₃, Y₂(C₂O₄)₃, Y₂(SO₄)₃, Zr(OH)₄, ZrO(OH)₂, ZrO2, ZrCl₄, ZrBr₄, ZrI₄, Zr(C₂O₄)₂, Zr(SO₄)₂, Ti(OH)₄, TiO(OH)₂, TiO2, TiCl₄, TiBr₄, TiI₄, Ti(C₂O₄)₂, Ti(SO₄)₂, BaO, Ba(OH)₂, BaCO₃, BaCl₂, BaBr₂, BaI₂, BaC₂O₄, BaSO₄, La(OH)₃, La₂O₃, LaCl₃, LaBr₃, LaI₃, La₂(C₂O₄)₃, La₂(SO₄)₃, Ce(OH)₄, CeO₂, Ce₂O₃, CeCl₄, CeBr₄, CeI₄, Ce(C₂O₄)₂, Ce(SO₄)₂, ThO₂, ThCl₄, ThBr₄, ThI₄, Th(OH)₄, Th(C₂O₄)₂, Th(SO₄)₂, Sr(OH)₂, SrCO₃, SrO, SrCl₂, SrBr₂, SrI₂, SrC₂O₄, SrSO₄, Sm₂O₃, SmCl₃, SmBr₃, SmI₃, Sm(OH)₃, Sm₂(CO₃)₃, Sm₂(C₂O₃)₃, Sm₂(SO₄)₃, LiCa₂Bi₃O₄Cl₆, Na₂WO₄, K/SrCoO₃, K/Na/SrCoO₃, Li/SrCoO₃, SrCoO₃, molybdenum oxides, molybdenum hydroxides, molybdenum chlorides, molybdenum bromides, molybdenum iodides, molybdenum oxalates, molybdenum sulfates, manganese oxides, manganese chlorides, manganese bromides, manganese iodides, manganese hydroxides, manganese oxalates, manganese sulfates, manganese tugstates, vanadium oxides, vanadium chlorides, vanadium bromides, vanadium iodides, vanadium hydroxides, vanadium oxalates, vanadium sulfates, tungsten oxides, tungsten chlorides, tungsten bromides, tungsten iodides, tungsten hydroxides, tungsten oxalates, tungsten sulfates, neodymium oxides, neodymium chlorides, neodymium bromides, neodymium iodides, neodymium hydroxides, neodymium oxalates, neodymium sulfates, europium oxides, europium chlorides, europium bromides, europium iodides, europium hydroxides, europium oxalates, europium sulfates rhenium oxides, rhenium chlorides, rhenium bromides, rhenium iodides, rhenium hydroxides, rhenium oxalates, rhenium sulfates, chromium oxides, chromium chlorides, chromium bromides, chromium iodides, chromium hydroxides, chromium oxalates, chromium sulfates, potassium molybdenum oxides and the like.

“Salt” means a compound comprising negative and positive ions. Salts are generally comprised of metallic cations and non-metallic counter ions. Under appropriate conditions, e.g., the solution also comprises a template, the metal ion (M^(n+)) and the anion (X^(m−)) bind to the template to induce nucleation and growth of a nanowire of M_(m)X_(n) on the template. “Anion precursor” thus is a compound that comprises an anion and a cationic counter ion, which allows the anion (X^(m−)) dissociate from the cationic counter ion in a solution. Specific examples of the metal salt and anion precursors are described in further detail herein.

“Oxide” refers to a metal compound comprising oxygen. Examples of oxides include, but are not limited to, metal oxides (M_(x)O_(y)), metal oxyhalide (M_(x)O_(y)X_(z)), metal oxynitrates (M_(x)O_(y)(NO₃)_(z)), metal phosphates (M_(x)(PO₄)_(y)), metal oxide carbonates (M_(x)O_(y)(CO₃)_(z)), metal carbonates and the like, wherein x, y and z are numbers from 1 to 100.

“Crystal domain” means a continuous region over which a substance is crystalline.

“Single-crystalline nanowires” means a nanowire having a single crystal domain.

“Template” is any synthetic and/or natural material that provides at least one nucleation site where ions can nucleate and grow to form nanoparticles. In certain embodiments, the templates can be a multi-molecular biological structure comprising one or more biomolecules. Typically, the biological template comprises multiple binding sites that recognize certain ions and allow for the nucleation and growth of the same. Non-limiting examples of biological templates include bacteriophages, amyloid fibers, viruses and capsids.

“Biomolecule” refers to any organic molecule of a biological origin. Biomolecule includes modified and/or degraded molecules of a biological origin. Non-limiting examples of biomolecules include peptides, proteins (including cytokines, growth factors, etc.), nucleic acids, polynucleotides, amino acids, antibodies, enzymes, and single-stranded or double-stranded nucleic acid, including any modified and/or degraded forms thereof.

“Amyloid fibers” refers to proteinaceous filaments of about 1-25 nm in diameter.

A “bacteriophage” or “phage” is any one of a number of viruses that infect bacteria. Typically, bacteriophages consist of an outer protein coat or “major coat protein” enclosing genetic material. A non-limiting example of a bacteriophage is the M13 bacteriophage. Non-limiting examples of bacteriophage coat proteins include the pill, pV, pVIII, etc. protein as described in more detail below.

A “capsid” is the protein shell of a virus. A capsid comprises several oligomeric structural subunits made of proteins.

“Nucleation” refers to the process of forming a solid from solubilized particles, for example forming a nanowire in situ by converting a soluble precursor (e.g. metal and hydroxide ions) into nanocrystals in the presence of a template.

“Nucleation site” refers to a site on a template, for example a bacteriophage, where nucleation of ions may occur. Nucleation sites include, for example, amino acids having carboxylic acid (—COOH), amino (—NH₃+ or —NH₂), hydroxyl (—OH), and/or thiol (—SH) functional groups.

A “peptide” refers to two or more amino acids joined by peptide (amide) bonds. The amino-acid building blocks (subunits) include naturally occurring α-amino acids and/or unnatural amino acids, such as β-amino acids and homoamino acids. An unnatural amino acid can be a chemically modified form of a natural amino acid. Peptides can be comprised of 2 or more, 5 or more, 10 or more, 20 or more, or 40 or more amino acids.

“Peptide sequence” refers to the sequence of amino acids within a peptide or protein.

“Protein” refers to a natural or engineered macromolecule having a primary structure characterized by peptide sequences. In addition to the primary structure, proteins also exhibit secondary and tertiary structures that determine their final geometric shapes.

“Polynucleotide” means a molecule comprised of two or more nucleotides connected via an internucleotide bond (e.g. a phosphate bond). Polynucleotides may be comprised of both ribose and/or deoxy ribose nucleotides. Examples of nucleotides include guanosine, adenosine, thiamine, and cytosine, as well as unnatural analogues thereof.

“Nucleic acid” means a macromolecule comprised of polynucleotides. Nucleic acids may be both single stranded and double stranded, and, like proteins, can exhibit secondary and tertiary structures that determine their final geometric shapes.

“Nucleic acid sequence” of “nucleotide sequence” refers to the sequence of nucleotides within a polynucleotide or nucleic acid.

“Anisotropic” means having an aspect ratio greater than one.

“Anisotropic biomolecule” means a biomolecule, as defined herein, having an aspect ratio greater than 1. Non-limiting examples of anisotropic biomolecules include bacteriophages, amyloid fibers, and capsids.

“Turnover number” is a measure of the number of reactant molecules a catalyst can convert to product molecules per unit time.

“Dopant” or “doping agent” is an impurity added to or incorporated within a catalyst to optimize catalytic performance (e.g. increase or decrease catalytic activity). As compared to the undoped catalyst, a doped catalyst may increase or decrease the selectivity, conversion, and/or yield of a reaction catalyzed by the catalyst.

“Atomic percent” (at %) or “atomic ratio” when used in the context of nanowire dopants refers to the ratio of the total number of dopant atoms to the total number of non-oxygen atoms in the nanowire. For example, the atomic percent of dopant in a lithium doped Mg₆MnO₈ nanowire is determined by calculating the total number of lithium atoms and dividing by the sum of the total number of magnesium and manganese atoms and multiplying by 100 (i.e., atomic percent of dopant=[Li atoms/(Mg atoms+Mn atoms)]×100)

“Group 1” elements include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

“Group 2” elements include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

“Group 3” elements include scandium (Sc) and yttrium (Y).

“Group 4” elements include titanium (Ti), zirconium (Zr), halfnium (Hf), and rutherfordium (Rf).

“Group 5” elements include vanadium (V), niobium (Nb), tantalum (Ta), and dubnium (Db).

“Group 6” elements include chromium (Cr), molybdenum (Mo), tungsten (W), and seaborgium (Sg).

“Group 7” elements include manganese (Mn), technetium (Tc), rhenium (Re), and bohrium (Bh).

“Group 8” elements include iron (Fe), ruthenium (Ru), osmium (Os), and hassium (Hs).

“Group 9” elements include cobalt (Co), rhodium (Rh), iridium (Ir), and meitnerium (Mt).

“Group 10” elements include nickel (Ni), palladium (Pd), platinum (Pt) and darmistadium (Ds).

“Group 11” elements include copper (Cu), silver (Ag), gold (Au), and roentgenium (Rg).

“Group 12” elements include zinc (Zn), cadmium (Cd), mercury (Hg), and copernicium (Cn).

“Lanthanides” include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), yitterbium (Yb), and lutetium (Lu).

“Actinides” include actinium (Ac), thorium (Th), protactinium (Pa), uranium (U), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berklelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), mendelevium (Md), nobelium (No), and lawrencium (Lr).

“Metal element” or “metal” is any element, except hydrogen, selected from Groups lthrough XII, lanthanides, actinides, aluminum (Al), gallium (Ga), indium (In), tin (Sn), thallium (TI), lead (Pb), and bismuth (Bi). Metal elements include metal elements in their elemental form as well as metal elements in an oxidized or reduced state, for example, when a metal element is combined with other elements in the form of compounds comprising metal elements. For example, metal elements can be in the form of hydrates, salts, oxides, as well as various polymorphs thereof, and the like.

“Semi-metal element” refers to an element selected from boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), and polonium (Po).

“Non-metal element” refers to an element selected from carbon (C), nitrogen (N), oxygen (O), fluorine (F), phosphorus (P), sulfur (S), chlorine (CI), selenium (Se), bromine (Br), iodine (I), and astatine (At).

“Conversion” means the mole fraction (i.e., percent) of a reactant converted to a product or products.

“Selectivity” refers to the percent of converted reactant that went to a specified product, e.g., C₂ selectivity is the % of methane that formed ethane and ethylene, C3 selectivity is the % of methane that formed propane and propylene, CO selectivity is the percent of methane that formed CO.

“Yield” is a measure of (e.g. percent) of product obtained relative to the theoretical maximum product obtainable. Yield is calculated by dividing the amount of the obtained product in moles by the theoretical yield in moles. Percent yield is calculated by multiplying this value by 100.

“Bulk catalyst” or “bulk material” means a catalyst prepared by traditional techniques, for example by milling or grinding large catalyst particles to obtain smaller/higher surface area catalyst particles. Bulk materials are prepared with minimal control over the size and/or morphology of the material.

“Alkane” means a straight chain or branched, noncyclic or cyclic, saturated aliphatic hydrocarbon. Alkanes include linear, branched and cyclic structures. Representative straight chain alkyls include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, and the like; while branched alkyls include isopropyl, sec-butyl, isobutyl, tert-butyl, isopentyl, and the like. Representative cyclic alkyls include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. “Alkene” means a straight chain or branched, noncyclic or cyclic, unsaturated aliphatic hydrocarbon having at least one carbon-carbon double bond. Alkenes include linear, branched and cyclic structures. Representative straight chain and branched alkenes include ethylenyl, propylenyl, 1-butenyl, 2-butenyl, isobutylenyl, 1-pentenyl, 2-pentenyl, 3-methyl-1-butenyl, 2-methyl-2-butenyl, 2,3-dimethyl-2-butenyl, and the like. Cyclic alkenes include cyclohexene and cyclopentene and the like.

“Alkyne” means a straight chain or branched, noncyclic or cyclic, unsaturated aliphatic hydrocarbon having at least one carbon-carbon triple bond. Alkynes include linear, branched and cyclic structures. Representative straight chain and branched alkynes include acetylenyl, propynyl, 1-butynyl, 2-butynyl, 1-pentynyl, 2-pentynyl, 3-methyl-1-butynyl, and the like. Representative cyclic alkynes include cycloheptyne and the like.

“Aromatic” means a carbocyclic moiety having a cyclic system of conjugated p orbitals forming a delocalized conjugated 7C system and a number of π electrons equal to 4n+2 with n=0, 1, 2, 3, etc. Representative examples of aromatics include benzene and naphthalene and toluene.

“Carbon-containing compounds” are compounds which comprise carbon. Non-limiting examples of carbon-containing compounds include hydrocarbons, CO and CO₂.

Nanowires

1. Structure/Physical Characteristics

FIG. 3A is a TEM image of a polycrystalline nanowire 200 having two distal ends 210 and 220. As shown, an actual length 230 essentially traces along the backbone of the nanowire 200, whereas an effective length 234 is the shortest distance between the two distal ends. The ratio of the effective length to the actual length is an indicator of the degrees of twists, bends and/or kinks in the general morphology of the nanowire. FIG. 3B is a schematic representation of the nanowire 200 of FIG. 3A. Typically, the nanowire is not uniform in its thickness or diameter. At any given location along the nanowire backbone, a diameter (240a, 240b, 240c, 240d) is the longest dimension of a cross section of the nanowire, i.e., is perpendicular to the axis of the nanowire backbone).

Compared to nanowire 200 of FIG. 3A, nanowire 250 of FIG. 4A has a different morphology and does not exhibit as many twists, bends and kinks, which suggests a different underlying crystal structure and different number of defects and/or stacking faults. As shown, for nanowire 250, the ratio of the effective length 270 and the actual length 260 is greater than the ratio of the effective length 234 and the actual length 240 of nanowire 200 of FIG. 3A. FIG. 4B is a schematic representation of the nanowire 250, which shows non-uniform diameters (280a, 280b, 280c and 280d).

As noted above, in some embodiments nanowires having a “bent” morphology (i.e. “bent nanowires”) are provided. A “bent’ morphology means that the bent nanowires comprise various twists, bends and/or kinks in their general morphology as illustrated generally in FIG. 3A and 3B and discussed above. Bent nanowires have a ratio of effective length to actual length of less than one. Accordingly, in some embodiments the present disclosure provides nanowires having a ratio of effective length to actual length of less than one. In other embodiments, the nanowires have a ratio of effective length to actual length of between 0.9 and 0.1, between 0.8 and 0.2, between 0.7 and 0.3, or between 0.6 and 0.4. In other embodiments, the ratio of effective length to actual length is less than 0.9, less than 0.8, less than 0.7, less than 0.6, less than 0.5, less than 0.4, less than 0.3, less than 0.2 or less than 0.1. In other embodiments, the ratio of effective length to actual length is less than 1.0 and more than 0.9, less than 1.0 and more than 0.8, less than 1.0 and more than 0.7, less than 1.0 and more than 0.6, less than 1.0 and more than 0.5, less than 1.0 and more than 0.4, less than 1.0 and more than 0.3, less than 1.0 and more than 0.2, or less than 1.0 and more than 0.1.

The ratio of effective length to actual length of a nanowire having a bent morphology may vary depending on the angle of observation. For example, one-skilled in the art will recognize that the same nanowire, when observed from different perspectives, can have a different effective length as determined by TEM. In addition, not all nanowires having a bent morphology will have the same ratio of effective length to actual length. Accordingly, in a population (i.e. plurality) of nanowires having a bent morphology, a range of ratios of effective length to actual length is expected. Although the ratio of effective length to actual length may vary from nanowire to nanowire, nanowires having a bent morphology will always have a ratio of effective length to actual length of less than one from any angle of observation.

In various embodiments, a substantially straight nanowire is provided. A substantially straight nanowire has a ratio of effective length to actual length equal to one. Accordingly, in some embodiments, the nanowires of the present disclosure have a ratio of effective length to actual length equal to one.

The actual lengths of the nanowires disclosed herein may vary. For example in some embodiments, the nanowires have an actual length of between 100 nm and 100 μm. In other embodiments, the nanowires have an actual length of between 100 nm and 10 μm. In other embodiments, the nanowires have an actual length of between 200 nm and 10 μm. In other embodiments, the nanowires have an actual length of between 500 nm and 5 μm. In other embodiments, the actual length is greater than 5 μm. In other embodiments, the nanowires have an actual length of between 800 nm and 1000 nm. In other further embodiments, the nanowires have an actual length of 900 nm. As noted below, the actual length of the nanowires may be determined by TEM, for example, in bright field mode at 5 keV.

The diameter of the nanowires may be different at different points along the nanowire backbone. However, the nanowires comprise a mode diameter (i.e. the most frequently occurring diameter). As used herein, the diameter of a nanowire refers to the mode diameter. In some embodiments, the nanowires have a diameter of between1 nm and 500 nm, between 1 nm and 100 nm, between 7 nm and 100 nm, between 7 nm and 50 nm, between 7 nm and 25 nm, or between 7 nm and 15 nm. On other embodiments, the diameter is greater than 500 nm. As noted below, the diameter of the nanowires may be determined by TEM, for example, in bright field mode at 5 keV.

Various embodiments of the present disclosure provide nanowires having different aspect ratios. In some embodiments, the nanowires have an aspect ratio of greater than 10:1. In other embodiments, the nanowires have an aspect ratio greater than 20:1. In other embodiments, the nanowires have an aspect ratio greater than 50:1. In other embodiments, the nanowires have an aspect ratio greater than 100:1.

In some embodiments, the nanowires comprise a solid core while in other embodiments, the nanowires comprise a hollow core.

The morphology of a nanowire (including length, diameter, and other parameters) can be determined by transmission electron microscopy (TEM). Transmission electron microscopy (TEM) is a technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through. An image is formed from the interaction of the electrons transmitted through the specimen. The image is magnified and focused onto an imaging device, such as a fluorescent screen, on a layer of photographic film or detected by a sensor such as a CCD camera. TEM techniques are well known to those of skill in the art.

A TEM image of nanowires may be taken, for example, in bright field mode at 5 keV (e.g., as shown in FIGS. 3A and 4A).

The nanowires of the present disclosure can be further characterized by powder x-ray diffraction (XRD). XRD is a technique capable of revealing information about the crystallographic structure, chemical composition, and physical properties of materials, including nanowires. XRD is based on observing the scattered intensity of an X-ray beam hitting a sample as a function of incident and scattered angle, polarization, and wavelength or energy.

Crystal structure, composition, and phase, including the crystal domain size of the nanowires, can be determined by XRD. In some embodiments, the nanowires comprise a single crystal domain (i.e. single crystalline). In other embodiments, the nanowires comprise multiple crystal domains (i.e. polycrystalline). In some other embodiments, the average crystal domain of the nanowires is less than 100 nm, less than 50 nm, less than 30 nm, less than 20 nm, less than 10 nm, less than 5nm, or less than 2 nm.

Typically, a catalytic material described herein comprises a plurality of nanowires. In certain embodiments, the plurality of nanowires form a mesh of randomly distributed and, to various degrees, interconnected nanowires. FIG. 5A is a TEM image of a nanowire mesh 300 comprising a plurality of nanowires 310 and a plurality of pores 320. FIG. 5B is a schematic representation of the nanowire mesh 300 of FIG. 5A.

The total surface area per gram of a nanowire or plurality of nanowires may have an effect on the catalytic performance. Pore size distribution may affect the nanowires catalytic performance as well. Surface area and pore size distribution of the nanowires or plurality of nanowires can be determined by BET (Brunauer, Emmett, Teller) measurements. BET techniques utilize nitrogen adsorption at various temperatures and partial pressures to determine the surface area and pore sizes of catalysts. BET techniques for determining surface area and pore size distribution are well known in the art.

In some embodiments the nanowires have a surface area of between 0.0001 and 3000 m²/g, between 0.0001 and 2000 m²/g, between 0.0001 and 1000 m²/g, between 0.0001 and 500 m²/g, between 0.0001 and 100 m²/g, between 0.0001 and 50 m²/g, between 0.0001 and 20 m²/g, between 0.0001 and 10 m²/g or between 0.0001 and 5 m²/g.

In some embodiments the nanowires have a surface area of between 0.001 and 3000 m²/g, between 0.001 and 2000 m²/g, between 0.001 and 1000 m²/g, between 0.001 and 500 m²/g, between 0.001 and 100 m²/g, between 0.001 and 50 m²/g, between 0.001 and 20 m²/g, between 0.001 and 10 m²/g or between 0.001 and 5 m²/g.

In some other embodiments the nanowires have a surface area of between 2000 and 3000 m²/g, between 1000 and 2000 m²/g, between 500 and 1000 m²/g, between 100 and 500 m²/g, between 10 and 100 m²/g, between 5 and 50 m²/g, between 2 and 20 m²/g or between 0.0001 and 10 m²/g.

In other embodiments, the nanowires have a surface area of greater than 2000 m²/g, greater than 1000 m²/g, greater than 500 m²/g, greater than 100 m²/g, greater than 50 m²/g, greater than 20 m²/g, greater than 10 m²/g, greater than 5 m²/g, greater than 1 m²/g, greater than 0.0001 m²/g.

2. Chemical Composition

As noted above, disclosed herein are nanowires useful as catalysts. The catalytic nanowires may have any number of compositions and morphologies. In some embodiments, the nanowires are inorganic. In other embodiments, the nanowires are polycrystalline. In some other embodiments, the nanowires are inorganic and polycrystalline. In yet other embodiments, the nanowires are single-crystalline, or in other embodiments the nanowires are inorganic and single-crystalline. In still other embodiments, the nanowires are amorphous, for example the nanowires may be amorphous, polycrystalline or single crystalline. In still other embodiments of any of the foregoing, the nanowires may have a ratio of effective length to actual length of less than one and an aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV. In still other embodiments of any of the forgoing, the nanowires may comprise one or more elements from any of Groups lthrough 7, lanthanides, actinides or combinations thereof

In some embodiments, the nanowires comprise one or more metal elements from any of Groups 1-7, lanthanides, actinides or combinations thereof, for example, the nanowires may be mono-metallic, bi-metallic, tri-metallic, etc (i.e. contain one, two, three, etc. metal elements). In some embodiments, the metal elements are present in the nanowires in elemental form while in other embodiments the metal elements are present in the nanowires in oxidized form. In other embodiments the metal elements are present in the nanowires in the form of a compound comprising a metal element. The metal element or compound comprising the metal element may be in the form of oxides, hydroxides, oxyhydroxides, salts, hydrates, oxide carbonates and the like. The metal element or compound comprising the metal element may also be in the form of any of a number of different polymorphs or crystal structures.

In certain examples, metal oxides may be hygroscopic and may change forms once exposed to air. Accordingly, although the nanowires are often referred to as metal oxides, in certain embodiments the nanowires also comprise hydrated oxides, oxyhydroxides, hydroxides or combinations thereof.

In other embodiments, the nanowires comprise one or more metal elements from Group I. In other embodiments, the nanowires comprise one or more metal elements from Group 2. In other embodiments, the nanowires comprise one or more metal elements from Group ₃. In other embodiments, the nanowires comprise one or more metal elements from Group 4. In other embodiments, the nanowires comprise one or more metal elements from Group 5. In other embodiments, the nanowires comprise one or more metal elements from Group 6. In other embodiments, the nanowires comprise one or more metal elements from Group 7. In other embodiments, the nanowires comprise one or more metal elements from the lanthanides. In other embodiments, the nanowires comprise one or more metal elements from the actinides.

In one embodiment, the nanowires comprise one or more metal elements from any of Groups 1-7, lanthanides, actinides or combinations thereof in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from Group 1 in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from Group 2 in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from Group 3 in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from Group 4 in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from Group 5 in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from Group 6 in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from Group 7 in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from the lanthanides in the form of an oxide. In another embodiment, the nanowires comprise one or more metal elements from the actinides in the form of an oxide.

In other embodiments, the nanowires comprise oxides, hydroxides, sulfates, carbonates, oxide carbonates, oxalates, phosphates (including hydrogenphosphates and dihydrogenphosphates), oxyhalides, hydroxihalides, oxyhydroxides, oxysulfates or combinations thereof of one or more metal elements from any of Groups 1-7, lanthanides, actinides or combinations thereof. In some other embodiments, the nanowires comprise oxides, hydroxides, sulfates, carbonates, oxide carbonates, oxalates or combinations thereof of one or more metal elements from any of Groups 1-7, lanthanides, actinides or combinations thereof. In other embodiments, the nanowires comprise oxides, and in other embodiments, the nanowires comprise hydroxides. In other embodiments, the nanowires comprise oxide carbonates. In other embodiments, the nanowires comprise Li₂CO₃, LiOH, Li₂O, Li₂C₂O₄, Li₂SO₄, Na₂CO₃, NaOH, Na₂O, Na₂C₂O₄, Na₂SO₄, K₂CO₃, KOH, K₂O, K₂C₂O₄, K₂SO₄, CsCO₃, CsOH, Cs₂O, CsC₂O₄, CsSO₄, Be(OH)₂, BeCO₃, BeO, BeC₂O₄, BeSO₄, Mg(OH)₂, MgCO₃, MgO, MgC₂O₄, MgSO₄, Ca(OH)₂, CaO, Ca(OH)₂, CaC₂O₄, CaSO₄, Y₂O₃, Y₂(CO3)₃, Y(OH)₃, Y₂(C₂O₄)₃,Y₂(SO₄)₃, Zr(OH)₄, ZrO(OH)₂, ZrO₂, Zr(C₂O₄)₂, Zr(SO₄)₂, Ti(OH)₄, TiO(OH)₂, TiO₂, Ti(C₂O₄)₂, Ti(SO₄)₂, BaO, Ba(OH)₂, BaCO₃, BaC₂O₄, BaSO₄, La(OH)₃, La₂O₃, La₂(C₂O₄)₃, La₂(SO₄)₃, Ce(OH)₄, CeO₂, Ce₂O₃, Ce(C₂O₄)₂, Ce(SO₄)₂, ThO₂, Th(OH)₄, Th(C₂O₄)₂, Th(SO₄)₂, Sr(OH)₂, SrCO₃, SrO, SrC₂O₄, SrSO₄, Sm₂O₃, Sm(OH)₃, Sm₂(CO₃)₃, Sm₂(C₂O₃)₃, Sm₂(SO₄)₃, LiCa₂Bi₃O₄Cl₆, NaMnO₄, Na₂WO₄, NaMn/WO₄, CoWO₄, CuWO₄, K/SrCoO₃, K/Na/SrCoO₃, Na/SrCoO₃, Li/SrCoO₃, SrCoO₃, Mg₆MnO₈, LiMn₂O₄, Li/Mg₆MnO₈, NaioMn/W₅O₁₇, Mg₃Mn₃B₂O₁₀, Mg₃(BO3)₂, molybdenum oxides, molybdenum hydroxides, molybdenum oxalates, molybdenum sulfates, Mn₂O₃, Mn₃O₄, manganese oxides, manganese hydroxides, manganese oxalates, manganese sulfates, manganese tungstates, vanadium oxides, vanadium hydroxides, vanadium oxalates, vanadium sulfates, tungsten oxides, tungsten hydroxides, tungsten oxalates, tungsten sulfates, neodymium oxides, neodymium hydroxides, neodymium oxalates, neodymium sulfates, europium oxides, europium hydroxides, europium oxalates, europium sulfates, praseodymium oxides, praseodymium hydroxides, praseodymium oxalates, praseodymium sulfates, rhenium oxides, rhenium hydroxides, rhenium oxalates, rhenium sulfates, chromium oxides, chromium hydroxides, chromium oxalates, chromium sulfates, potassium molybdenum oxides/silicon oxide or combinations thereof.

In other embodiments, the nanowires comprise Li₂O, Na₂O, K₂O, Cs₂O, BeO MgO, CaO, ZrO(OH)₂, ZrO2, TiO₂, TiO(OH)₂, BaO, Y₂O₃, La₂O₃, CeO₂, Ce₂O₃, ThO₂, SrO, Sm₂O₃, Nd₂O₃, Eu₂O₃, Pr₂O₃, LiCa₂Bi₃O₄Cl₆, NaMnO₄, Na₂WO₄, Na/Mn/WO₄, Na/MnWO₄, Mn/WO₄, K/SrCoO₃, K/Na/SrCoO₃, K/SrCoO₃, Na/SrCoO₃, Li/SrCoO₃, SrCoO₃, Mg₆MnO₈, Na/B/Mg₆MnO₈, Li/B/Mg₆MnO₈, Zr₂Mo₂O₈, molybdenum oxides, Mn₂O₃, Mn₃O₄, manganese oxides, vanadium oxides, tungsten oxides, neodymium oxides, rhenium oxides, chromium oxides, or combinations thereof.

In still other aspects, the nanowires comprise lanthanide containing perovskites. A perovskite is any material with the same type of crystal structure as calcium titanium oxide (CaTiO₃). Examples of perovskites within the context of the present disclosure include, but are not limited to, LaCoO₃ and La/SrCoO₃.

In other embodiments, the nanowires comprise TiO₂, Sm₂O₃, V₂O₅, MoO₃, BeO, MnO₂, MgO, La₂O₃, Nd₂O₃, Eu₂O₃, ZrO₂, SrO, Na₂WO₄, Mn/WO₄, BaCO₃, Mn₂O₃, Mn₃O₄, Mg₆MnO₈, Na/B/Mg₆MnO₈, Li/B/Mg₆MnO₈, NaMnO₄, CaO or combinations thereof. In further embodiments, the nanowires comprise MgO, La₂O₃, Nd₂O3, Na₂WO₄, Mn/WO₄, Mn₂O₃, Mn₃O₄, Mg₆MnO₈, Na/B/Mg₆MnO₈, Li/B/Mg₆MnO₈ or combinations thereof.

In some embodiments, the nanowires comprises Mg, Ca, La, W, Mn, Mo, Nd, Sm, Eu, Pr, Zr or combinations thereof, and in other embodiments the nanowire comprises MgO, CaO, La₂O₃, Na₂WO₄, Mn₂O₃, Mn₃O₄, Nd₂O₃, Sm₂O₃, Eu₂O₃, Pr₂O₃, Mg₆MnO₈, NaMnO₄, Na/Mn/W/O, Na/MnWO₄, MnWO₄ or combinations thereof.

In more specific embodiments, the nanowires comprise MgO. In other specific embodiments, the nanowires comprise La₂O₃. In other specific embodiments, the nanowires comprise Na₂WO₄ and may optionally further comprise Mn/WO₄. In other specific embodiments, the nanowires comprise Mn₂O₃. In other specific embodiments, the nanowires comprise Mn₃O₄. In other specific embodiments, the nanowires comprise Mg₆MnO₈. In other specific embodiments, the nanowires comprise NaMnO₄. In other specific embodiments, the nanowires comprise Nd₂O₃. In other specific embodiments, the nanowires comprise Eu2O₃. In other specific embodiments, the nanowires comprise Pr₂O_(3.)

In certain embodiments, the nanowires comprise an oxide of a group 2 element. For example, in some embodiments, the nanowires comprise an oxide of magnesium. In other embodiments, the nanowires comprise an oxide of calcium. In other embodiments, the nanowires comprise an oxide of strontium. In other embodiments, the nanowires comprise an oxide of barium.

In certain other embodiments, the nanowires comprise an oxide of a group 3 element. For example, in some embodiments, the nanowires comprise an oxide of yttrium. In other embodiments, the nanowires comprise an oxide of scandium.

In yet other certain embodiments, the nanowires comprise an oxide of an early lanthanide element. For example, in some embodiments, the nanowires comprise an oxide of lanthanum. In other embodiments, the nanowires comprise an oxide of cerium. In other embodiments, the nanowires comprise an oxide of praseodymium. In other embodiments, the nanowires comprise an oxide of neodymium. In other embodiments, the nanowires comprise an oxide of promethium. In other embodiments, the nanowires comprise an oxide of samarium. In other embodiments, the nanowires comprise an oxide of europium. In other embodiments, the nanowires comprise an oxide of gandolinium.

In certain other embodiments, the nanowires comprise a lanthanide in the form of an oxide carbonate. For example, the nanowires may comprise Ln₂O₂(CO₃), where Ln represents a lanthanide. Examples in this regard include: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu oxide carbonates. In other embodiments, the nanowires comprise an oxide carbonate of one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof. Accordingly in one embodiment the nanowires comprise Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc or Re oxide carbonate. In other embodiments, the nanowires comprise Ac, Th or Pa oxide carbonate. An oxide carbonate may be represented by the following formula: M_(x)O_(y)(CO₃)_(z), wherein M is a metal element from any of Groups 1 through 7, lanthanides or actinides and x, y and z are intergers such that the overall charge of the metal oxide carbonate is neutral.

In other embodiments, the nanowires comprise TiO₂, Sm₂O₂, V₂O₅, MoO₃, BeO, MnO₂, MgO, La₂O₃, ZrO₂, SrO, Na₂WO₄, BaCO₃, Mn₂O₃, Mn₃O₄, Mg₆MnO₈, Na/B/Mg₆MnO₈, Li/B/Mg₆MnO₈, Zr₂Mo₂O₈, NaMnO₄, CaO or combinations thereof and further comprise one or more dopants comprised of metal elements, semi-metal elements, non-metal elements or combinations thereof. In some further embodiments, the nanowires comprise MgO, La₂O₃, Na₂WO₄, Mn₂O₃, Mn₃O₄, Mg₆MnO₈, Zr₂Mo₂O₈, NaMnO₄ or combinations thereof, and the nanowires further comprise Li, Sr, Zr, Ba, Mn or Mn/WO₄.

In some embodiments, the nanowires or a catalytic material comprising a plurality of the nanowires comprise a combination of one or more of metal elements from any of Groups 1-7, lanthanides or actinides and one or more of metal elements, semi-metal elements or non-metal elements. For example in one embodiment, the nanowires comprise the combinations of Li/Mg/O, Ba/Mg/O, Zr/La/O, Ba/La/O, Sr/La/O, Zr/V/P/O, Mo/V/Sb/O, V₂O₅/Al₂O₃, Mo/V/O, V/Ce/O, ViTi/P/O, V₂O₅/TiO₂, V/P/O/TiO₂, V/P/O/Al₂O₃, V/Mg/O, V₂O₅/ZrO₂, Mo/V/Te/O, V/Mo/O/Al₂O₃, Ni/V/Sb/O, Co/V/Sb/O, SniV/Sb/O, Bi/V/Sb/O, Mo/V/Te/Nb/O, Mo/V/Nb/O, V₂O₅/MgO/SiO₂, V/Co, MoO₃/Al₂O₃, Ni/Nb/O, NiO/Al₂O₃, Ga/CriZr/P/O, MoO₃/Cl/SiO₂/TiO₂, Co/Cr/Sn/W/O, Cr/Mo/O, MoO₃/Cl/SiO₂/TiO₂, Co/Ca, NiO/MgO, MoO₃/Al₂O₃, Nb/P/Mo/O, Mo/V/Te/Sbi/Nb/O, La/Na/Al/O, Ni/Ta/Nb/O, Mo/Mn/V/W/O, Li/Dy/Mg/O, Sr/La/Nd/O, Co/CriSn/W/O, MoO₃/SiO₂/TiO₂, Sm/Na/P/O, Sm/Sr/O, Sr/La/Nd/O, Co/P/O/TiO₂, La/Sr/Fe/Cl/O, La/Sr/Cu/Cl/O, Y/Ba/Cu/O, Na/Ca/O, V₂O₅/ZrO₂, V/Mg/O, Mn/V/Cr/W/O/Al₂O₃, V₂O₅/K/SiO₂, V₂O₅/Ca/TiO₂, V₂O₅/K/TiO₂, V/Mg/Al/O, V/Zr/O, V/Nb/O, V₂O₅/Ga₂O₃, V/Mg/Al/O, V/Nb/O, V/Sb/O, V/Mn/O, V/Nb/O/Sb₂O₄, V/Sb/O/TiO₂, V₂O₅/Ca, V₂O₅/K/Al₂O₃, V₂O₅/TiO₂, V₂O₅/MgO/TiO₂, V₂O₅/ZrO₂, V/Al/F/O, V/Nb/O/TiO₂, Ni/V/O, V₂O₅/SmVO₄, V/W/O, V₂O₅/Zn/Al₂O₃, V₂O₅/CeO₂, V/Sm/O, V₂O₅/TiO₂/SiO₂, Mo/Li/O/Al₂O₃, Mg/Dy/Li/Cl/O, Mg/Dy/Li/Cl/O, Ce/Ni/O, Ni/Mo/O/V, Ni/Mo/O/V/N, Ni/Mo/O Sb/O/N, MoO₃/Cl/SiO₂/TiO₂, Co/Mo/O, Ni/Ti/O, Ni/Zr/O, Cr/O, MoO₃/Al₂O₃, Mn/P/O, MoO₃/K/ZrO₂, Na/W/O, Mn/Na/W/O, Mn/Na/W/O/SiO₂, Na/W/O/SiO₂, Mn/Mo/O, Nb₂O₅/TiO₂, Co/W/O, Ni/Mo/O, Ga/Mo/O, Mg/Mo/V/O, Cr₂O₃/Al₂O₃, Cr/Mo/Cs/O/Al₂O₃, Co/Sr/O/Ca, Ag/Mo/P/O, MoO₃/SmVO₄, Mo/Mg/Al/O, MoO₃/K/SiO₂/TiO₂, CriMo/O/Al₂O₃, MoO₃/Al₂O₃, Ni/Co/Mo/O, Y/Zr/O, Y/Hf, Zr/Mo/Mn/O, Mg/Mn/O, Li/Mn/O, Mg/Mn/B/O, Mg/B/O, Na/B/Mg/Mn/O, Li/B/Mg/Mn/O, Mn/Na/P/O, Na/Mn/Mg/O, Zr/Mo/O, Mn/W/O or Mg/Mn/O.

In a specific embodiment, the nanowires comprise the combinations of Li/Mg/O, Ba/Mg/O, Zr/La/O, Ba/La/O, Sr/La/O, Sr/Nd/O, La/O, Nd/O, Eu/O, Mg/La/O, Mg/Nd/O, Na/La/O, Na/Nd/O, Sm/O, Mn/Na/W/O, Mg/Mn/O, Na/B/Mg/Mn/O, Li/B/Mg/Mn/O, Zr/Mo/O or Na/Mn/Mg/O. For example, in some embodiments the nanowires comprise the combinations of Li/MgO, Ba/MgO, Sr/La₂O₃, Ba/La₂O₃, Mn/Na₂WO₄, MniNa₂WO₄/SiO₂, Mn₂O₃/Na₂WO₄, Mn₃O₄/Na₂WO₄, Li/B/Mg₆MnO₈, Na/B/Mg₆MnO₈ or NaMnO₄/MgO. In certain embodiments, the nanowire comprises Li/MgO, Ba/MgO, Sr/La₂O₃, Mg/Na/La₂O₃, Sr/Nd₂O₃, or Mn/Na₂WO₄.

In some other specific embodiments, the nanowires comprise the combination of Li/MgO. In other specific embodiments, the nanowires comprise the combination of Ba/MgO. In other specific embodiments, the nanowires comprise the combination of Sr/La₂O₃. In other specific embodiments, the nanowires comprise the combination of Ba/La₂O₃. In other specific embodiments, the nanowires comprise the combination of Mn/Na₂WO₄. In other specific embodiments, the nanowires comprise the combination of Mn/Na₂WO₄/SiO₂. In other specific embodiments, the nanowires comprise the combination of Mn₂O₃/Na₂WO₄. In other specific embodiments, the nanowires comprise the combination of Mn₃O₄/Na₂WO₄. In other specific embodiments, the nanowires comprise the combination of Mn/WO₄/Na₂WO₄. In other specific embodiments, the nanowires comprise the combination of Li/B/Mg₆MnO₈. In other specific embodiments, the nanowires comprise the combination of Na/B/Mg₆MnO₈. In other specific embodiments, the nanowires comprise the combination of NaMnO₄/MgO.

Polyoxyometalates (POM) are a class of metal oxides that range in structure from the molecular to the micrometer scale. The unique physical and chemical properties of POM clusters, and the ability to tune these properties by synthetic means have attracted significant interest from the scientific community to create “designer” materials. For example, heteropolyanions such as the well-known Keggin [XM₁₂O₄₀]⁻ and Wells-Dawson [X₂M1₈O₆₂]⁻ anions (where M=W or Mo; and X=a tetrahedral template such as but not limited to Si, Ge, P) and isopolyanions with metal oxide frameworks with general formulas [MO_(x)]_(n) where M=Mo, W, V, and Nb and x=4-7 are ideal candidates for OCM/ODH catalysts. Accordingly, in one embodiment the nanowires comprise [XM₁₂O₄₀]⁻ or [X₂M1₈O₆₂]⁻ anions (where M=W or Mo; and X=a tetrahedral template such as but not limited to Si, Ge, P) and isopolyanions with metal oxide frameworks with general formulas [MO_(x)]_(n) where M=Mo, W, V, and Nb and x=4-7. In some embodiments, X is P or Si.

These POM clusters have “lacunary” sites that can accommodate divalent and trivalent first row transition metals, the metal oxide clusters acting as ligands. These lacunary sites are essentially “doping” sites, allowing the dopant to be dispersed at the molecular level instead of in the bulk which can create pockets of unevenly dispersed doped material. Because the POM clusters can be manipulated by standard synthetic techniques, POMs are highly modular and a wide library of materials can be prepared with different compositions, cluster size, and dopant oxidation state. These parameters can be tuned to yield desired OCM/ODH catalytic properties. Accordingly, one embodiment of the present disclosure is a nanowire comprising one or more POM clusters. Such nanowires find utility as catalysts, for example, in the OCM and ODH reactions.

Silica doped sodium manganese tungstate (NaMn/WO₄/SiO₂) is a promising OCM catalyst. The NaMn/WO₄/SiO₂ system is attractive due to its high C2 selectivity and yield. Unfortunately, good catalytic activity is only achievable at temperatures greater than 800° C. and although the exact active portion of the catalyst is still subject to debate, it is thought that sodium plays an important role in the catalytic cycle. In addition, the NaMn/WO₄/SiO₂ catalyst surface area is relatively low <2m²/g. Manganese tungstate (Mn/WO₄) nanorods (i.e., straight nanowires) can be used to model a NaMn/WO₄/SiO₂ based nanowire OCM catalyst. The Mn/WO₄ nanorods are prepared hydro-thermally and the size can be tuned based on reaction conditions with dimensions of 25-75 nm in diameter to 200-800 nm in length. The as-prepared nano-rods have higher surface areas than the NaMn/WO₄/SiO₂ catalyst systems. In addition, the amount of sodium, or other elements, can precisely doped into the Mn/WO₄ nanorod material to target optimal catalytic activity. Nanorod tungstate based materials can be expanded to but, not limited to, CoWO₄ or CuWO₄ materials which may serve as base materials for OCM/ODH catalysis. In addition to straight nanowires, the above discussion applies to the disclosed nanowires having a bent morphology as well. The nanowires of the disclosure may be analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to determine the element content of the nanowires. ICP-MS is a type of mass spectrometry that is highly sensitive and capable of the determination of a range of metals and several non-metals at concentrations below one part in 10¹². ICP is based on coupling together an inductively coupled plasma as a method of producing ions (ionization) with a mass spectrometer as a method of separating and detecting the ions. ICP-MS methods are well known in the art.

In some embodiments, the nanowire comprises a combination of two or more metal compounds, for example metal oxides. For example, in some embodiments, the nanowire comprises Mn₂O₃/Na₂WO₄, Mn₃O₄/Na₂WO₄ MnWO₄/Na₂WO₄/Mn₂O₃, MnWO₄/Na₂WO₄/Mn₃O₄ or NaMnO₄/MgO.

₃. Catalytic Materials

As noted above, the present disclosure provides a catalytic material comprising a plurality of nanowires. In certain embodiments, the catalytic material comprises a support or carrier. The support is preferably porous and has a high surface area. In some embodiments the support is active (i.e. has catalytic activity). In other embodiments, the support is inactive (i.e. non-catalytic). In some embodiments, the support comprises an inorganic oxide, Al₂O₃, SiO₂, TiO₂, MgO, ZrO₂, ZnO, LiAlO₂, MgAl₂O₄, MnO, MnO₂, Mn₃O₄, La₂O₃, AlPO₄, SiO₂/Al₂O₃, activated carbon, silica gel, zeolites, activated clays, activated Al₂O₃, diatomaceous earth, magnesia, aluminosilicates, calcium aluminate, support nanowires or combinations thereof. In some embodiments the support comprises silicon, for example SiO₂. In other embodiments the support comprises magnesium, for example MgO. In other embodiments the support comprises zirconium, for example ZrO₂. In yet other embodiments, the support comprises lanthanum, for example La₂O₃. In yet other embodiments, the support comprises hafnium, for example HfO₂. In yet other embodiments, the support comprises aluminum, for example Al₂O₃. In yet other embodiments, the support comprises gallium, for example Ga₂O₃.

In still other embodiments, the support material comprises an inorganic oxide, Al₂O₃, SiO₂, TiO₂, MgO, ZrO₂, HfO2, CaO, ZnO, LiAlO₂, MgAl₂O₄, MnO, MnO₂, Mn₂O₄, Mn₃O₄, La₂O₃, activated carbon, silica gel, zeolites, activated clays, activated Al₂O₃, diatomaceous earth, magnesia, aluminosilicates, calcium aluminate, support nanowires or combinations thereof. For example, the support material may comprise SiO₂, ZrO₂, CaO, La₂O₃ or MgO.

In yet other embodiments, a nanowire may serve as a support for another nanowire. For example, a nanowire may be comprised of non-catalytic metal elements and adhered to or incorporated within the support nanowire is a catalytic nanowire. For example, in some embodiments, the support nanowires are comprised of SiO₂, MgO, TiO₂, ZrO₂, Al₂O₃, or ZnO. Preparation of nanowire supported nanowire catalysts (i.e., core/shell nanowires) is discussed in more detail below. The optimum amount of nanowire present on the support depends, inter alia, on the catalytic activity of the nanowire. In some embodiments, the amount of nanowire present on the support ranges from 1 to 100 parts by weight nanowires per 100 parts by weight of support or from 10 to 50 parts by weight nanowires per 100 parts by weight of support. In other embodiments, the amount of nanowire present on the support ranges from 100-200 parts of nanowires per 100 parts by weight of support, or 200-500 parts of nanowires per 100 parts by weight of support, or 500-1000 parts of nanowires per 100 parts by weight of support.

Typically, heterogeneous catalysts are used either in their pure form or blended with inert materials, such as silica, alumina, etc. The blending with inert materials is used in order to reduce and/or control large temperature non-uniformities within the reactor bed often observed in the case of strongly exothermic (or endothermic) reactions. In the case of complex multistep reactions, such as the reaction to convert methane into ethylene (OCM), typical blending materials can selectively slow down or quench one or more of the reactions of the system and promote unwanted side reactions. For example, in the case of the oxidative coupling of methane, silica and alumina can quench the methyl radicals and thus prevent the formation of ethane. In certain aspects, the present disclosure provides a catalytic material which solves these problems typically associated with catalyst support material. Accordingly, in certain embodiments the catalytic activity of the catalytic material can be tuned by blending two or more catalysts and/or catalyst support materials. The blended catalytic material may comprise a catalytic nanowire as described herein and a bulk catalyst material and/or inert support material.

The blended catalytic materials comprise metal oxides, hydroxides, oxy-hydroxides, carbonates, oxalates of the groups 1-16, lanthanides, actinides or combinations thereof. For example, the blended catalytic materials may comprise a plurality of inorganic catalytic polycrystalline nanowires, as disclosed herein, and any one or more of straight nanowires, nanoparticles, bulk materials and inert support materials. Bulk materials are defined as any material in which no attempt to control the size and/or morphology was performed during its synthesis. The catalytic materials may be undoped or may be doped with any of the dopants described herein.

In one embodiment, the catalyst blend comprises at least one type 1 component and at least one type 2 component. Type 1 components comprise catalysts having a high OCM activity at moderately low temperatures and type 2 components comprise catalysts having limited or no OCM activity at these moderately low temperatures, but are OCM active at higher temperatures. For example, in some embodiments the type 1 component is a catalyst (e.g., nanowire) having high OCM activity at moderately low temperatures. For example, the type 1 component may comprise a C2 yield of greater than 5% or greater than 10% at temperatures less than 800° C., less than 700° C. or less than 600° C. The type 2 component may comprise a C2 yield less than 0.1%, less than 1% or less than 5% at temperatures less than 800° C., less than 700° C. or less than 600° C. The type 2 component may comprise a C2 yield of greater than 0.1%, greater than 1%, greater than 5% or greater than 10% at temperatures greater than 800° C., greater than 700° C. or greater than 600° C. Typical type 1 components include nanowires, for example polycrystalline nanowires as described herein, while typical type 2 components include bulk OCM catalysts and nanowire catalysts which only have good OCM activity at higher temperatures, for example greater than 800° C. Examples of type 2 components may include catalysts comprising MgO. The catalyst blend may further comprise inert support materials as described above (e.g., silica, alumina, etc.).

In certain embodiments, the type 2 component acts as diluent in the same way an inert material does and thus helps reduce and/or control hot spots in the catalyst bed caused by the exothermic nature of the OCM reaction. However, because the type 2 component is an OCM catalyst, albeit not a particularly active one, it may prevent the occurrence of undesired side reactions, e.g. methyl radical quenching. Additionally, controlling the hotspots has the beneficial effect of extending the lifetime of the catalyst.

For example, it has been found that diluting active lanthanide oxide OCM catalysts (e.g., nanowires) with as much as a 10:1 ratio of MgO, which by itself is not an active OCM catalyst at the temperature which the lanthanide oxide operates, is a good way to minimize “hot spots” in the reactor catalyst bed, while maintaining the selectivity and yield performance of the catalyst. On the other hand, doing the same dilution with quartz SiO₂ is not effective because it appears to quench the methyl radicals which serves to lower the selectivity to C2s.

In yet another embodiment, the type 2 components are good oxidative dehydrogenation (ODH) catalysts at the same temperature that the type 1 components are good OCM catalysts. In this embodiment, the ethylene/ethane ratio of the resulting gas mixture can be tuned in favor of higher ethylene. In another embodiment, the type 2 components are not only good ODH catalysts at the same temperature the type 1 components are good OCM catalysts, but also have limited to moderate OCM activity at these temperatures.

In related embodiments, the catalytic performance of the catalytic material is tuned by selecting specific type 1 and type 2 components of a catalyst blend. In another embodiment, the catalytic performance is tuned by adjusting the ratio of the type 1 and type 2 components in the catalytic material. For example, the type 1 catalyst may be a catalyst for a specific step in the catalytic reaction, while the type 2 catalyst may be specific for a different step in the catalytic reaction. For example, the type 1 catalyst may be optimized for formation of methyl radicals and the type 2 catalyst may be optimized for formation of ethane or ethylene.

In other embodiments, the catalyst material comprises at least two different components (component 1, component 2, component 3, etc.). The different components may comprise different morphologies, e.g. nanowires, nanoparticles, bulk, etc. The different components in the catalyst material can be, but not necessarily, of the same chemical composition and the only difference is in the morphology and/or the size of the particles. This difference in morphology and particle size may result in a difference in reactivity at a specific temperature. Additionally, the difference in morphology and particle size of the catalytic material components is advantageous for creating a very intimate blending, e.g. very dense packing of the catalysts particles, which can have a beneficial effect on catalyst performance. Also, the difference in morphology and particle size of the blend components would allow for control and tuning of the macro-pore distribution in the reactor bed and thus its catalytic efficiency. An additional level of micro-pore tuning can be attained by blending catalysts with different chemical composition and different morphology and/or particle size. The proximity effect would be advantageous for the reaction selectivity.

Accordingly, in one embodiment the present disclosure provides the use of a catalytic material comprising a first catalytic nanowire and a bulk catalyst and/or a second catalytic nanowire in a catalytic reaction, for example the catalytic reaction may be OCM or ODH. In other embodiments, the first catalytic nanowire and the bulk catalyst and/or second catalytic nanowire are each catalytic with respect to the same reaction, and in other examples the first catalytic nanowire and the bulk catalyst and/or second catalytic nanowire have the same chemical composition.

In some specific embodiments of the foregoing, the catalytic material comprises a first catalytic nanowire and a second catalytic nanowire. Each nanowire can have completely different chemical compositions or they may have the same base composition and differ only by the doping elements. In other embodiments,each nanowire can have the same or a different morphology. For example, each nanowire can differ by the nanowire size (length and/or aspect ratio), by ratio of actual/effective length, by chemical composition or any combination thereof. Furthermore, the first and second nanowires may each be catalytic with resepect to the same reaction but may have different activity. Alternatively, each nanowire may catalyze different reactions.

In a related embodiment, the catalytic material comprises a first catalytic nanowire and a bulk catalyst. The first nanowire and the bulk catalyst can have completely different chemical compositions or they may have the same base composition and differ only by the doping elements. Furthermore, the first nanowire and the bulk catalyst may each be catalytic with resepect to the same reaction but may have different activity. Alternatively, the first nanowire and the bulk catalyst may catalyze different reactions.

In yet other embodiments of the foregoing, the catalytic nanowire has a catalytic activity in the catalytic reaction which is greater than a catalytic activity of the bulk catalyst in the catalytic reaction at the same temperature. In still other embodiments, the catalytic activity of the bulk catalyst in the catalytic reaction increases with increasing temperature.

For ease of illustration, the above description of catalytic materials often refers to OCM; however, such catalytic materials find utility in other catalytic reactions including but not limited to: oxidative dehydrogenation (ODH) of alkanes to their corresponding alkenes, selective oxidation of alkanes and alkenes and alkynes, oxidation of co, dry reforming of methane, selective oxidation of aromatics, Fischer-Tropsch, combustion of hydrocarbons, etc.

4. Preparation of Catalytic Materials

The catalytic materials can be prepared according to any number of methods known in the art. For example, the catalytic materials can be prepared after preparation of the individual components by mixing the individual components in their dry form, e.g. blend of powders, and optionally, ball milling can be used to reduce particle size and/or increase mixing. Each component can be added together or one after the other to form layered particles. Alternatively, the individual components can be mixed prior to calcination, after calcination or by mixing already calcined components with uncalcined components. The catalytic materials may also be prepared by mixing the individual components in their dry form and optionally pressing them together into a “pill” followed by calcination to above 400° C.

In other examples, the catalytic materials are prepared by mixing the individual components with one or more solvents into a suspension or slurry, and optional mixing and/or ball milling can be used to maximize uniformity and reduce particle size. Examples of slurry solvents useful in this context include, but are not limited to: water, alcohols, ethers, carboxylic acids, ketones, esters, amides, aldehydes, amines, alkanes, alkenes, alkynes, aromatics, etc. In other embodiments, the individual components are deposited on a supporting material such as silica, alumina, magnesia, activated carbon, and the like, or by mixing the individual components using a fluidized bed granulator. Combinations of any of the above methods may also be used.

The catalytic materials may optionally comprise a dopant as described in more detail below. In this respect, doping material(s) may be added during preparation of the individual components, after preparation of the individual components but before drying of the same, after the drying step but before calcinations or after calcination. If more than one doping material is used, each dopant can be added together or one after the other to form layers of dopants.

Doping material(s) may also be added as dry components and optionally ball milling can be used to increase mixing. In other embodiments, doping material(s) are added as a liquid (e.g. solution, suspension, slurry, etc.) to the dry individual catalyst components or to the blended catalytic material. The amount of liquid may optionally be adjusted for optimum wetting of the catalyst, which can result in optimum coverage of catalyst particles by doping material. Mixing and/or ball milling can also be used to maximize doping coverage and uniform distribution. Alternatively, doping material(s) are added as a liquid (e.g. solution, suspension, slurry, etc.) to a suspension or slurry of the catalyst in a solvent. Mixing and/or ball milling can be used to maximize doping coverage and uniform distribution. Incorporation of dopants can also be achieved using any of the methods described elsewhere herein.

As noted below, an optional calcination step usually follows an optional drying step at T<200C (typically 60-120C) in a regular oven or in a vacuum oven. Calcination may be performed on the individual components of the catalytic material or on the blended catalytic material. Calcination is generally performed in an oven/furnace at a temperature higher than the minimum temperature at which at least one of the components decomposes or undergoes a phase transformation and can be performed in inert atmosphere (e.g. N₂, Ar, He, etc.), oxidizing atmosphere (air, O₂, etc.) or reducing atmosphere (H₂, H₂/N₂, H₂/Ar, etc.). The atmosphere may be a static atmosphere or a gas flow and may be performed at ambient pressure, at p<1atm, in vacuum or at p>1atm. High pressure treatment (at any temperature) may also be used to induce phase transformation including amorphous to crystalline.

Calcination is generally performed in any combination of steps comprising ramp up, dwell and ramp down. For example, ramp to 500° C., dwell at 500° C. for 5h, ramp down to RT. Another example includes ramp to 100° C., dwell at 100° C. for 2h, ramp to 300° C., dwell at 300° C. for 4h, ramp to 550° C., dwell at 550° C. for 4h, ramp down to RT. Calcination conditions (pressure, atmosphere type, etc.) can be changed during the calcination. In some embodiments, calcination is performed before preparation of the blended catalytic material (i.e., individual components are calcined), after preparation of the blended catalytic material but before doping, after doping of the individual components or blended catalytic material. Calcination may also be performed multiple times, e.g. after catalyst preparation and after doping.

The catalytic materials may incorporated into a reactor bed for performing any number of catalytic reactions (e.g., OCM, ODH and the like). In this regard, the catalytic material may be packed neat (without diluents) or diluted with an inert material (e.g., sand, silica, alumina, etc.) The catalyst components may be packed uniformly forming a homogeneous reactor bed.

The particle size of the individual components within a catalytic material may also alter the catalytic activity, and other properties, of the same. Accordingly, in one embodiment, the catalyst is milled to a target average particle size or the catalyst powder is sieved to select a particular particle size. In some aspects, the catalyst powder may be pressed into pellets and the catalyst pellets can be optionally milled and or sieved to obtain the desired particle size distribution.

In yet another embodiment, the catalysts are packed in bands forming a layered reactor bed. Each layer is composed by either a catalyst of a particular type, morphology or size or a particular blend of catalysts. In one embodiment, the catalysts blend may have better sintering properties, i.e. lower tendency to sinter, then a material in its pure form. Better sintering resistance is expected to increase the catalyst's lifetime and improve the mechanical properties of the reactor bed.

In yet other embodiments, the disclosure provides a catalytic material comprising one or more different catalysts. The catalysts may be a nanowire as disclosed herein and a different catalyst for example a bulk catalysts. Mixture of two or more nanowire catalysts are also contemplated. The catalytic material may comprise a catalyst, for example a nanowire catalyst, having good OCM activity and a catalyst having good activity in the ODH reaction. Either one or both of these catalysts may be nanowires as disclosed herein.

On skilled in the art will recognize that various combinations or alternatives of the above methods are possible, and such variations are also included within the scope of the present disclosure.

5. Dopants

In further embodiments, the disclosure provides nanowires comprising a dopant (i.e., doped nanowires). As noted above, dopants or doping agents are impurities added to or incorporated within a catalyst to optimize catalytic performance (e.g., increase or decrease catalytic activity). As compared to the undoped catalyst, a doped catalyst may increase or decrease the selectivity, conversion, and/or yield of a catalytic reaction. In one embodiment, nanowire dopants comprise one or more metal elements, semi-metal elements, non-metal elements or combinations thereof. The dopant may be present in any form and may be derived from any suitable source of the element (e.g., chlorides, nitrates, etc.). In some embodiments, the nanowire dopant is in elemental form. In other embodiments, the nanowire dopant is in reduced or oxidized form. In other embodiments, the nanowire dopant comprises an oxide, hydroxide, carbonate, nitrate, acetate, sulfate, formate, oxynitrate, halide, oxyhalide or hydroxyhalide of a metal element, semi-metal element or non-metal element or combinations thereof.

In one embodiment, the nanowires comprise one or more metal elements selected from Groups 1-7, lanthanides, actinides or combinations thereof in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from group 1 in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from group 2 in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from group 3 in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from group 4 in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from group V in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from group 6 in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from group 7 in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from lanthanides in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof. In another embodiment, the nanowires comprise one or more metal elements selected from actinides in the form of an oxide and further comprise one or more dopants, wherein the one or more dopants comprise metal elements, semi-metal elements, non-metal elements or combinations thereof.

For example, in one embodiment, the nanowire dopant comprises Li, Li₂CO₃, LiOH, Li₂O, LiCl, LiNO₃, Na, Na₂CO₃, NaOH, Na₂O, NaCl, NaNO₃, K, K₂CO₃, KOH, K₂O, KCl, KNO₃, Rb, Rb₂CO₃, RbOH, Rb₂O, RbCl, RbNO₃, Mg, MgCO₃, Mg(OH)₂, MgO, MgCl₂, Mg(NO₃)₂, Ca, CaO, CaCO₃, Ca(OH)₂, CaCl₂, Ca(NO₃)₂, Sr, SrO, SrCO₃, Sr(OH)₂, SrCl₂, Sr(NO₃)₂, Ba, BaO, BaCO₃, Ba(OH)₂, BaCl₂, Ba(NO₃)₂, La, La₂O₃, La(OH)₃, LaCl₃, La(NO₃)₂, Nb, Nb₂O₃, Nb(OH)₃, NbCl₃, Nb(NO₃)₂, Sm, Sm₂O₂, Sm(OH)₃, SmCl₃, Sm(NO₃)₂, Eu, Eu₂O₃, Eu(OH)₃, EuCl₃, Eu(NO₃)₂, Gd, Gd₂O₃, Gd(OH)₃, GdCl₃, Gd(NO₃)₂, Ce, Ce(OH)₄, CeO₂, Ce₂O₃, CeCl₄, Ce(NO₃)₂, Th, ThO₂, ThCl₄, Th(OH)₄, Zr, ZrO₂, ZrCl₄, Zr(OH)₄, ZrOCl₂, ZrO(NO₃)₂, P, phosphorous oxides, phosphorous chlorides, phosphorous carbonates, Ni, nickel oxides, nickel chlorides, nickel carbonates, nickel hydroxides, Nb, niobium oxides, niobium chlorides, niobium carbonates, niobium hydroxides, Au, gold oxides, gold chlorides, gold carbonates, gold hydroxides, Mo, molybdenum oxides, molybdenum chlorides, molybdenum carbonates, molybdenum hydroxides, tungsten chlorides, tungsten carbonates, tungsten hydroxides, Cr, chromium oxides, chromium chlorides, chromium hydroxides, Mn, manganese oxides, manganese chlorides, manganese hydroxides, Zn, ZnO, ZnCl₂, Zn(OH)₂, B, borates, BCl₃, N, nitrogen oxides, nitrates, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. In, Y, Sc, Al, Cu, Cs, Ga, Hf, Fe, Ru, Rh, Be, Co, Sb, V, Ag, Te, Pd, Tb, Ir, Rb or combinations thereof. In other embodiments, the nanowire dopant comprises Na, Eu. In, Nd, Sm, Ce, Gd, Y, Sc or combinations thereof.

In other embodiments, the nanowire dopant comprises Li, Li₂O, Na, Na₂O, K, K₂O, Mg, MgO, Ca, CaO, Sr, SrO, Ba, BaO, La, La₂O₃, Ce, CeO₂, Ce₂O₃, Th, ThO₂, Zr, ZrO₂, P, phosphorous oxides, Ni, nickel oxides, Nb, niobium oxides, Au, gold oxides, Mo, molybdenum oxides, Cr, chromium oxides, Mn, manganese oxides, Zn, ZnO, B, borates, N, nitrogen oxides or combinations thereof. In other embodiments, the nanowire dopant comprises Li, Na, K, Mg, Ca, Sr, Ba, La, Ce, Th, Zr, P, Ni, Nb, Au, Mo, Cr, Mn, Zn, B, N or combinations thereof. In other embodiments, the nanowire dopant comprises Li₂O, Na₂O, K₂O, MgO, CaO, SrO, BaO, La₂O₃, CeO₂, Ce₂O₃, ThO₂, ZrO₂, phosphorous oxides, nickel oxides, niobium oxides, gold oxides, molybdenum oxides, chromium oxides, manganese oxides, ZnO, borates, nitrogen oxides or combinations thereof. In further embodiments, the dopant comprises Sr or Li. In other specific embodiments, the nanowire dopant comprises La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. In, Y, Sc or combinations thereof. In other specific embodiments, the nanowire dopant comprises Li, Na, K, Mg, Ca, Ba, Sr, Eu, Sm, Co or Mn.

In certain embodiments, the dopant comprises an element from group 1. In some embodiments, the dopant comprises lithium. In some embodiments, the dopant comprises sodium. In some embodiments, the dopant comprises potassium. In some embodiments, the dopant comprises rubidium. In some embodiments, the dopant comprises caesium.

In some embodiments the nanowires comprise a lanthanide element and are doped with a dopant from group 1, group 2, or combinations thereof. For example, in some embodiments, the nanowires comprise a lanthanide element and are doped with lithium. In other embodiments, the nanowires comprise a lanthanide element and are doped with sodium. In other embodiments, the nanowires comprise a lanthanide element and are doped with potassium. In other embodiments, the nanowires comprise a lanthanide element and are doped with rubidium. In other embodiments, the nanowires comprise a lanthanide element and are doped with caesium. In other embodiments, the nanowires comprise a lanthanide element and are doped with beryllium. In other embodiments, the nanowires comprise a lanthanide element and are doped with magnesium. In other embodiments, the nanowires comprise a lanthanide element and are doped with calcium. In other embodiments, the nanowires comprise a lanthanide element and are doped with strontium. In other embodiments, the nanowires comprise a lanthanide element and are doped with barium.

In some embodiments the nanowires comprise a transition metal tungstate (e.g., Mn/W and the like) and are doped with a dopant from group 1, group 2, or combinations thereof. For example, in some embodiments, the nanowires comprise a transition metal tungstate and are doped with lithium. In other embodiments, the nanowires comprise a transition metal tungstate and are doped with sodium. In other embodiments, the nanowires comprise a transition metal tungstate and are doped with potassium. In other embodiments, the nanowires comprise a transition metal tungstate and are doped with rubidium. In other embodiments, the nanowires comprise a transition metal tungstate and are doped with caesium. In other embodiments, the nanowires comprise a transition metal tungstate and are doped with beryllium. In other embodiments, the nanowires comprise a transition metal tungstate and are doped with magnesium. In other embodiments, the nanowires comprise a transition metal tungstate and are doped with calcium. In other embodiments, the nanowires comprise a transition metal tungstate and are doped with strontium. In other embodiments, the nanowires comprises a transition metal tungstate and are doped with barium.

In some embodiments the nanowires comprise Mn/Mg/O and are doped with a dopant from group 1, group 2, group 7, group 8, group 9 or group 10 or combinations thereof. For example, in some embodiments, the nanowires comprise Mn/Mg/O and are doped with lithium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with sodium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with potassium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with rubidium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with caesium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with beryllium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with magnesium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with calcium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with strontium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with barium.

In yet some other embodiments, the nanowires comprise Mn/Mg/O and are doped with manganese. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with technetium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with rhenium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with bohrium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with iron. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with ruthenium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with osmium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with hassium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with cobalt. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with rhodium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with iridium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with meitnerium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with nickel. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with palladium. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with platinum. In other embodiments, the nanowires comprise Mn/Mg/O and are doped with darmistadtium.

It is contemplated that any one or more of the dopants disclosed herein can be combined with any one of the nanowires disclosed herein to form a doped nanowire comprising one, two, three or more dopants. Tables 1-8 below show exemplary doped nanowires in accordance with various specific embodiments. In some embodiments, the doped nanowires shown in tables 1-8 are doped with one, two, three or more additional dopants.

TABLE 1 NANOWIRES (NW) DOPED WITH SPECIFIC DOPANTS (DOP) NW\Dop Li Na K Rb Li₂O Li/Li₂O Na/Li₂O K/Li₂O Rb/Li₂O Na₂O Li/Na₂O Na/Na₂O K/Na₂O Rb/Na₂O K₂O Li/K₂O Na/K₂O K/K₂O Rb/K₂O Rb₂O Li/Rb₂O Na/Rb₂O K/Rb₂O Rb/Rb₂O Cs₂O Li/Cs₂O Na/Cs₂O K/Cs₂O Rb/Cs₂O BeO Li/BeO Na/BeO K/BeO Rb/BeO MgO Li/MgO Na/MgO K/MgO Rb/MgO CaO Li/CaO Na/CaO K/CaO Rb/CaO SrO Li/SrO Na/SrO K/SrO Rb/SrO BaO Li/BaO Na/BaO K/BaO Rb/BaO Sc₂O₃ Li/Sc₂O₃ Na/Sc₂O₃ K/Sc₂O₃ Rb/Sc₂O₃ Y₂O₃ Li/Y₂O₃ Na/Y₂O₃ K/Y₂O₃ Rb/Y₂O₃ La₂O₃ Li/La₂O₃ Na/La₂O₃ K/La₂O₃ Rb/La₂O₃ CeO₂ Li/CeO₂ Na/CeO₂ K/CeO₂ Rb/CeO₂ Ce₂O₃ Li/Ce₂O₃ Na/Ce₂O₃ K/Ce₂O₃ Rb/Ce₂O₃ Pr₂O₃ Li/Pr₂O₃ Na/Pr₂O₃ K/Pr₂O₃ Rb/Pr₂O₃ Nd₂O₃ Li/Nd₂O₃ Na/Nd₂O₃ K/Nd₂O₃ Rb/Nd₂O₃ Sm₂O₃ Li/Sm₂O₃ Na/Sm₂O₃ K/Sm₂O₃ Rb/Sm₂O₃ Eu₂O₃ Li/Eu₂O₃ Na/Eu₂O₃ K/Eu₂O₃ Rb/Eu₂O₃ Gd₂O₃ Li/Gd₂O₃ Na/Gd₂O₃ K/Gd₂O₃ Rb/Gd₂O₃ Tb₂O₃ Li/Tb₂O₃ Na/Tb₂O₃ K/Tb₂O₃ Rb/Tb₂O₃ TbO₂ Li/TbO₂ Na/TbO₂ K/TbO₂ Rb/TbO₂ Tb₆O₁₁ Li/Tb₆O₁₁ Na/Tb₆O₁₁ K/Tb₆O₁₁ Rb/Tb₆O₁₁ Dy₂O₃ Li/Dy₂O₃ Na/Dy₂O₃ K/Dy₂O₃ Rb/Dy₂O₃ Ho₂O₃ Li/Ho₂O₃ Na/Ho₂O₃ K/Ho₂O₃ Rb/Ho₂O₃ Er₂O₃ Li/Er₂O₃ Na/Er₂O₃ K/Er₂O₃ Rb/Er₂O₃ Tm₂O₃ Li/Tm₂O₃ Na/Tm₂O₃ K/Tm₂O₃ Rb/Tm₂O₃ Yb₂O₃ Li/Yb₂O₃ Na/Yb₂O₃ K/Yb₂O₃ Rb/Yb₂O₃ Lu₂O₃ Li/Lu₂O₃ Na/Lu₂O₃ K/Lu₂O₃ Rb/Lu₂O₃ Ac₂O₃ Li/Ac₂O₃ Na/Ac₂O₃ K/Ac₂O₃ Rb/Ac₂O₃ Th₂O₃ Li/Th₂O₃ Na/Th₂O₃ K/Th₂O₃ Rb/Th₂O₃ ThO₂ Li/ThO₂ Na/ThO₂ K/ThO₂ Rb/ThO₂ Pa₂O₃ Li/Pa₂O₃ Na/Pa₂O₃ K/Pa₂O₃ Rb/Pa₂O₃ PaO₂ Li/PaO₂ Na/PaO₂ K/PaO₂ Rb/PaO₂ TiO₂ Li/TiO₂ Na/TiO₂ K/TiO₂ Rb/TiO₂ TiO Li/TiO Na/TiO K/TiO Rb/TiO Ti₂O₃ Li/Ti₂O₃ Na/Ti₂O₃ K/Ti₂O₃ Rb/Ti₂O₃ Ti₃O Li/Ti₃O Na/Ti₃O K/Ti₃O Rb/Ti₃O Ti₂O Li/Ti₂O Na/Ti₂O K/Ti₂O Rb/Ti₂O Ti₃O₅ Li/Ti₃O₅ Na/Ti₃O₅ K/Ti₃O₅ Rb/Ti₃O₅ Ti₄O₇ Li/Ti₄O₇ Na/Ti₄O₇ K/Ti₄O₇ Rb/Ti₄O₇ ZrO₂ Li/ZrO₂ Na/ZrO₂ K/ZrO₂ Rb/ZrO₂ HfO₂ Li/HfO₂ Na/HfO₂ K/HfO₂ Rb/HfO₂ VO Li/VO Na/VO K/VO Rb/VO V₂O₃ Li/V₂O₃ Na/V₂O₃ K/V₂O₃ Rb/V₂O₃ VO₂ Li/VO₂ Na/VO₂ K/VO₂ Rb/VO₂ V₂O₅ Li/V₂O₅ Na/V₂O₅ K/V₂O₅ Rb/V₂O₅ V₃O₇ Li/V₃O₇ Na/V₃O₇ K/V₃O₇ Rb/V₃O₇ V₄O₉ Li/V₄O₉ Na/V₄O₉ K/V₄O₉ Rb/V₄O₉ V₆O₁₃ Li/V₆O₁₃ Na/V₆O₁₃ K/V₆O₁₃ Rb/V₆O₁₃ NbO Li/NbO Na/NbO K/NbO Rb/NbO NbO₂ Li/NbO₂ Na/NbO₂ K/NbO₂ Rb/NbO₂ Nb₂O₅ Li/Nb₂O₅ Na/Nb₂O₅ K/Nb₂O₅ Rb/Nb₂O₅ Nb₈O₁₉ Li/Nb₈O₁₉ Na/Nb₈O₁₉ K/Nb₈O₁₉ Rb/Nb₈O₁₉ Nb₁₆O₃₈ Li/Nb₁₆O₃₈ Na/Nb₁₆O₃₈ K/Nb₁₆O₃₈ Rb/Nb₁₆O₃₈ Nb₁₂O₂₉ Li/Nb₁₂O₂₉ Na/Nb₁₂O₂₉ K/Nb₁₂O₂₉ Rb/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Li/Nb₄₇O₁₁₆ Na/Nb₄₇O₁₁₆ K/Nb₄₇O₁₁₆ Rb/Nb₄₇O₁₁₆ Ta₂O₅ Li/Ta₂O₅ Na/Ta₂O₅ K/Ta₂O₅ Rb/Ta₂O₅ CrO Li/CrO Na/CrO K/CrO Rb/CrO Cr₂O₃ Li/Cr₂O₃ Na/Cr₂O₃ K/Cr₂O₃ Rb/Cr₂O₃ CrO₂ Li/CrO₂ Na/CrO₂ K/CrO₂ Rb/CrO₂ CrO₃ Li/CrO₃ Na/CrO₃ K/CrO₃ Rb/CrO₃ Cr₈O₂₁ Li/Cr₈O₂₁ Na/Cr₈O₂₁ K/Cr₈O₂₁ Rb/Cr₈O₂₁ MoO₂ Li/MoO₂ Na/MoO₂ K/MoO₂ Rb/MoO₂ MoO₃ Li/MoO₃ Na/MoO₃ K/MoO₃ Rb/MoO₃ W₂O₃ Li/W₂O₃ Na/W₂O₃ K/W₂O₃ Rb/W₂O₃ WoO₂ Li/WoO₂ Na/WoO₂ K/WoO₂ Rb/WoO₂ WoO₃ Li/WoO₃ Na/WoO₃ K/WoO₃ Rb/WoO₃ MnO Li/MnO Na/MnO K/MnO Rb/MnO Mn/Mg/O Li/Mn/Mg/O Na/Mn/Mg/O K/Mn/Mg/O Rb/Mn/Mg/O Mn₃O₄ Li/Mn₃O₄ Na/Mn₃O₄ K/Mn₃O₄ Rb/Mn₃O₄ Mn₂O₃ Li/Mn₂O₃ Na/Mn₂O₃ K/Mn₂O₃ Rb/Mn₂O₃ MnO₂ Li/MnO₂ Na/MnO₂ K/MnO₂ Rb/MnO₂ Mn₂O₇ Li/Mn₂O₇ Na/Mn₂O₇ K/Mn₂O₇ Rb/Mn₂O₇ ReO₂ Li/ReO₂ Na/ReO₂ K/ReO₂ Rb/ReO₂ ReO₃ Li/ReO₃ Na/ReO₃ K/ReO₃ Rb/ReO₃ Re₂O₇ Li/Re₂O₇ Na/Re₂O₇ K/Re₂O₇ Rb/Re₂O₇ Mg₃Mn₃— B₂O₁₀ Li/Mg₃Mn₃— B₂O₁₀ Na/Mg₃Mn₃— B₂O₁₀ K/Mg₃Mn₃— B₂O₁₀ Rb/Mg₃Mn₃— B₂O₁₀ Mg₃(BO₃)₂ Li/Mg₃(BO₃)₂ Na/Mg₃(BO₃)₂ K/Mg₃(BO₃)₂ Rb/Mg₃(BO₃)₂ NaWO₄ Li/NaWO₄ Na/NaWO₄ K/NaWO₄ Rb/NaWO₄ Mg₆MnO₈ Li/Mg₆MnO₈ Na/Mg₆MnO₈ K/Mg₆MnO₈ Rb/Mg₆MnO₈ (Li,Mg)₆— MnO₈ Li/(Li,Mg)₆— MnO₈ Na/(Li,Mg)₆— MnO₈ K/(Li,Mg)₆— MnO₈ Rb/(Li,Mg)₆— MnO₈ Mn₂O₄ Li/Mn₂O₄ Na/Mn₂O₄ K/Mn₂O₄ Rb/Mn₂O₄ Na₄P₂O₇ Li/Na₄P₂O₇ Na/Na₄P₂O₇ K/Na₄P₂O₇ Rb/Na₄P₂O₇ Mo₂O₈ Li/Mo₂O₈ Na/Mo₂O₈ K/Mo₂O₈ Rb/Mo₂O₈ Mn₃O₄/WO₄ Li/Mn₃O₄/WO₄ Na/Mn₃O₄/WO₄ K/Mn₃O₄/WO₄ Rb/Mn₃O₄/WO₄ Na₂WO₄ Li/Na₂WO₄ Na/Na₂WO₄ K/Na₂WO₄ Rb/Na₂WO₄ Zr₂Mo₂O₈ Li/Zr₂Mo₂O₈ Na/Zr₂Mo₂O₈ K/Zr₂Mo₂O₈ Rb/Zr₂Mo₂O₈ NaMnO₄—/MgO Li/NaMnO₄—/MgO Na/NaMnO₄—/MgO K/NaMnO₄—/MgO Rb/NaMnO₄—/MgO Na₁₀Mn— W₅O₁₇ Li/Na₁₀Mn— W₅O₁₇ Na/Na₁₀Mn— W₅O₁₇ K/Na₁₀Mn— W₅O₁₇ Rb/Na₁₀Mn— W₅O₁₇ NW\Dop Cs Be Mg Ca Li₂O Cs/Li₂O Be/Li₂O Mg/Li₂O Ca/Li₂O Na₂O Cs/Na₂O Be/Na₂O Mg/Na₂O Ca/Na₂O K₂O Cs/K₂O Be/K₂O Mg/K₂O Ca/K₂O Rb₂O Cs/Rb₂O Be/Rb₂O Mg/Rb₂O Ca/Rb₂O Cs₂O Cs/Cs₂O Be/Cs₂O Mg/Cs₂O Ca/Cs₂O BeO Cs/BeO Be/BeO Mg/BeO Ca/BeO MgO Cs/MgO Be/MgO Mg/MgO Ca/MgO CaO Cs/CaO Be/CaO Mg/CaO Ca/CaO SrO Cs/SrO Be/SrO Mg/SrO Ca/SrO BaO Cs/BaO Be/BaO Mg/BaO Ca/BaO Sc₂O₃ Cs/Sc₂O₃ Be/Sc₂O₃ Mg/Sc₂O₃ Ca/Sc₂O₃ Y₂O₃ Cs/Y₂O₃ Be/Y₂O₃ Mg/Y₂O₃ Ca/Y₂O₃ La₂O₃ Cs/La₂O₃ Be/La₂O₃ Mg/La₂O₃ Ca/La₂O₃ CeO₂ Cs/CeO₂ Be/CeO₂ Mg/CeO₂ Ca/CeO₂ Ce₂O₃ Cs/Ce₂O₃ Be/Ce₂O₃ Mg/Ce₂O₃ Ca/Ce₂O₃ Pr₂O₃ Cs/Pr₂O₃ Be/Pr₂O₃ Mg/Pr₂O₃ Ca/Pr₂O₃ Nd₂O₃ Cs/Nd₂O₃ Be/Nd₂O₃ Mg/Nd₂O₃ Ca/Nd₂O₃ Sm₂O₃ Cs/Sm₂O₃ Be/Sm₂O₃ Mg/Sm₂O₃ Ca/Sm₂O₃ Eu₂O₃ Cs/Eu₂O₃ Be/Eu₂O₃ Mg/Eu₂O₃ Ca/Eu₂O₃ Gd₂O₃ Cs/Gd₂O₃ Be/Gd₂O₃ Mg/Gd₂O₃ Ca/Gd₂O₃ Tb₂O₃ Cs/Tb₂O₃ Be/Tb₂O₃ Mg/Tb₂O₃ Ca/Tb₂O₃ TbO₂ Cs/TbO₂ Be/TbO₂ Mg/TbO₂ Ca/TbO₂ Tb₆O₁₁ Cs/Tb₆O₁₁ Be/Tb₆O₁₁ Mg/Tb₆O₁₁ Ca/Tb₆O₁₁ Dy₂O₃ Cs/Dy₂O₃ Be/Dy₂O₃ Mg/Dy₂O₃ Ca/Dy₂O₃ Ho₂O₃ Cs/Ho₂O₃ Be/Ho₂O₃ Mg/Ho₂O₃ Ca/Ho₂O₃ Er₂O₃ Cs/Er₂O₃ Be/Er₂O₃ Mg/Er₂O₃ Ca/Er₂O₃ Tm₂O₃ Cs/Tm₂O₃ Be/Tm₂O₃ Mg/Tm₂O₃ Ca/Tm₂O₃ Yb₂O₃ Cs/Yb₂O₃ Be/Yb₂O₃ Mg/Yb₂O₃ Ca/Yb₂O₃ Lu₂O₃ Cs/Lu₂O₃ Be/Lu₂O₃ Mg/Lu₂O₃ Ca/Lu₂O₃ Ac₂O₃ Cs/Ac₂O₃ Be/Ac₂O₃ Mg/Ac₂O₃ Ca/Ac₂O₃ Th₂O₃ Cs/Th₂O₃ Be/Th₂O₃ Mg/Th₂O₃ Ca/Th₂O₃ ThO₂ Cs/ThO₂ Be/ThO₂ Mg/ThO₂ Ca/ThO₂ Pa₂O₃ Cs/Pa₂O₃ Be/Pa₂O₃ Mg/Pa₂O₃ Ca/Pa₂O₃ PaO₂ Cs/PaO₂ Be/PaO₂ Mg/PaO₂ Ca/PaO₂ TiO₂ Cs/TiO₂ Be/TiO₂ Mg/TiO₂ Ca/TiO₂ TiO Cs/TiO Be/TiO Mg/TiO Ca/TiO Ti₂O₃ Cs/Ti₂O₃ Be/Ti₂O₃ Mg/Ti₂O₃ Ca/Ti₂O₃ Ti₃O Cs/Ti₃O Be/Ti₃O Mg/Ti₃O Ca/Ti₃O Ti₂O Cs/Ti₂O Be/Ti₂O Mg/Ti₂O Ca/Ti₂O Ti₃O₅ Cs/Ti₃O₅ Be/Ti₃O₅ Mg/Ti₃O₅ Ca/Ti₃O₅ Ti₄O₇ Cs/Ti₄O₇ Be/Ti₄O₇ Mg/Ti₄O₇ Ca/Ti₄O₇ ZrO₂ Cs/ZrO₂ Be/ZrO₂ Mg/ZrO₂ Ca/ZrO₂ HfO₂ Cs/HfO₂ Be/HfO₂ Mg/HfO₂ Ca/HfO₂ VO Cs/VO Be/VO Mg/VO Ca/VO V₂O₃ Cs/V₂O₃ Be/V₂O₃ Mg/V₂O₃ Ca/V₂O₃ VO₂ Cs/VO₂ Be/VO₂ Mg/VO₂ Ca/VO₂ V₂O₅ Cs/V₂O₅ Be/V₂O₅ Mg/V₂O₅ Ca/V₂O₅ V₃O₇ Cs/V₃O₇ Be/V₃O₇ Mg/V₃O₇ Ca/V₃O₇ V₄O₉ Cs/V₄O₉ Be/V₄O₉ Mg/V₄O₉ Ca/V₄O₉ V₆O₁₃ Cs/V₆O₁₃ Be/V₆O₁₃ Mg/V₆O₁₃ Ca/V₆O₁₃ NbO Cs/NbO Be/NbO Mg/NbO Ca/NbO NbO₂ Cs/NbO₂ Be/NbO₂ Mg/NbO₂ Ca/NbO₂ Nb₂O₅ Cs/Nb₂O₅ Be/Nb₂O₅ Mg/Nb₂O₅ Ca/Nb₂O₅ Nb₈O₁₉ Cs/Nb₈O₁₉ Be/Nb₈O₁₉ Mg/Nb₈O₁₉ Ca/Nb₈O₁₉ Nb₁₆O₃₈ Cs/Nb₁₆O₃₈ Be/Nb₁₆O₃₈ Mg/Nb₁₆O₃₈ Ca/Nb₁₆O₃₈ Nb₁₂O₂₉ Cs/Nb₁₂O₂₉ Be/Nb₁₂O₂₉ Mg/Nb₁₂O₂₉ Ca/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Cs/Nb₄₇O₁₁₆ Be/Nb₄₇O₁₁₆ Mg/Nb₄₇O₁₁₆ Ca/Nb₄₇O₁₁₆ Ta₂O₅ Cs/Ta₂O₅ Be/Ta₂O₅ Mg/Ta₂O₅ Ca/Ta₂O₅ CrO Cs/CrO Be/CrO Mg/CrO Ca/CrO Cr₂O₃ Cs/Cr₂O₃ Be/Cr₂O₃ Mg/Cr₂O₃ Ca/Cr₂O₃ CrO₂ Cs/CrO₂ Be/CrO₂ Mg/CrO₂ Ca/CrO₂ CrO₃ Cs/CrO₃ Be/CrO₃ Mg/CrO₃ Ca/CrO₃ Cr₈O₂₁ Cs/Cr₈O₂₁ Be/Cr₈O₂₁ Mg/Cr₈O₂₁ Ca/Cr₈O₂₁ MoO₂ Cs/MoO₂ Be/MoO₂ Mg/MoO₂ Ca/MoO₂ MoO₃ Cs/MoO₃ Be/MoO₃ Mg/MoO₃ Ca/MoO₃ W₂O₃ Cs/W₂O₃ Be/W₂O₃ Mg/W₂O₃ Ca/W₂O₃ WoO₂ Cs/WoO₂ Be/WoO₂ Mg/WoO₂ Ca/WoO₂ WoO₃ Cs/WoO₃ Be/WoO₃ Mg/WoO₃ Ca/WoO₃ MnO Cs/MnO Be/MnO Mg/MnO Ca/MnO Mn/Mg/O Cs/Mn/Mg/O Be/Mn/Mg/O Mg/Mn/Mg/O Ca/Mn/Mg/O Mn₃O₄ Cs/Mn₃O₄ Be/Mn₃O₄ Mg/Mn₃O₄ Ca/Mn₃O₄ Mn₂O₃ Cs/Mn₂O₃ Be/Mn₂O₃ Mg/Mn₂O₃ Ca/Mn₂O₃ MnO₂ Cs/MnO₂ Be/MnO₂ Mg/MnO₂ Ca/MnO₂ Mn₂O₇ Cs/Mn₂O₇ Be/Mn₂O₇ Mg/Mn₂O₇ Ca/Mn₂O₇ ReO₂ Cs/ReO₂ Be/ReO₂ Mg/ReO₂ Ca/ReO₂ ReO₃ Cs/ReO₃ Be/ReO₃ Mg/ReO₃ Ca/ReO₃ Re₂O₇ Cs/Re₂O₇ Be/Re₂O₇ Mg/Re₂O₇ Ca/Re₂O₇ Mg₃Mn₃— B₂O₁₀ Cs/Mg₃Mn₃— B₂O₁₀ Be/Mg₃Mn₃— B₂O₁₀ Mg/Mg₃Mn₃— B₂O₁₀ Ca/Mg₃Mn₃— B₂O₁₀ Mg₃(BO₃)₂ Cs/Mg₃(BO₃)₂ Be/Mg₃(BO₃)₂ Mg/Mg₃(BO₃)₂ Ca/Mg₃(BO₃)₂ NaWO₄ Cs/NaWO₄ Be/NaWO₄ Mg/NaWO₄ Ca/NaWO₄ Mg₆MnO₈ Cs/Mg₆MnO₈ Be/Mg₆MnO₈ Mg/Mg₆MnO₈ Ca/Mg₆MnO₈ (Li,Mg)₆— MnO₈ Cs/(Li,Mg)₆— MnO₈ Be/(Li,Mg)₆— MnO₈ Mg/(Li,Mg)₆— MnO₈ Ca/(Li,Mg)₆— MnO₈ Mn₂O₄ Cs/Mn₂O₄ Be/Mn₂O₄ Mg/Mn₂O₄ Ca/Mn₂O₄ Na₄P₂O₇ Cs/Na₄P₂O₇ Be/Na₄P₂O₇ Mg/Na₄P₂O₇ Ca/Na₄P₂O₇ Mo₂O₈ Cs/Mo₂O₈ Be/Mo₂O₈ Mg/Mo₂O₈ Ca/Mo₂O₈ Mn₃O₄/WO₄ Cs/Mn₃O₄/WO₄ Be/Mn₃O₄/WO₄ Mg/Mn₃O₄/WO₄ Ca/Mn₃O₄/WO₄ Na₂WO₄ Cs/Na₂WO₄ Be/Na₂WO₄ Mg/Na₂WO₄ Ca/Na₂WO₄ Zr₂Mo₂O₈ Cs/Zr₂Mo₂O₈ Be/Zr₂Mo₂O₈ Mg/Zr₂Mo₂O₈ Ca/Zr₂Mo₂O₈ NaMnO₄—/MgO Cs/NaMnO₄—/MgO Be/NaMnO₄—/MgO Mg/NaMnO₄—/MgO Ca/NaMnO₄—/MgO Na₁₀Mn— W₅O₁₇ Cs/Na₁₀Mn— W₅O₁₇ Be/Na₁₀Mn— W₅O₁₇ Mg/Na₁₀Mn— W₅O₁₇ Ca/Na₁₀Mn— W₅O₁₇

TABLE 2 NANOWIRES (NW) DOPED WITH SPECIFIC DOPANTS (DOP) NW\Dop Sr Ba B P Li₂O Sr/Li₂O Ba/Li₂O B/Li₂O P/Li₂O Na₂O Sr/Na₂O Ba/Na₂O B/Na₂O P/Na₂O K₂O Sr/K₂O Ba/K₂O B/K₂O P/K₂O Rb₂O Sr/Rb₂O Ba/Rb₂O B/Rb₂O P/Rb₂O Cs₂O Sr/Cs₂O Ba/Cs₂O B/Cs₂O P/Cs₂O BeO Sr/BeO Ba/BeO B/BeO P/BeO MgO Sr/MgO Ba/MgO B/MgO P/MgO CaO Sr/CaO Ba/CaO B/CaO P/CaO SrO Sr/SrO Ba/SrO B/SrO P/SrO BaO Sr/BaO Ba/BaO B/BaO P/BaO Sc₂O₃ Sr/Sc₂O₃ Ba/Sc₂O₃ B/Sc₂O₃ P/Sc₂O₃ Y₂O₃ Sr/Y₂O₃ Ba/Y₂O₃ B/Y₂O₃ P/Y₂O₃ La₂O₃ Sr/La₂O₃ Ba/La₂O₃ B/La₂O₃ P/La₂O₃ CeO₂ Sr/CeO₂ Ba/CeO₂ B/CeO₂ P/CeO₂ Ce₂O₃ Sr/Ce₂O₃ Ba/Ce₂O₃ B/Ce₂O₃ P/Ce₂O₃ Pr₂O₃ Sr/Pr₂O₃ Ba/Pr₂O₃ B/Pr₂O₃ P/Pr₂O₃ Nd₂O₃ Sr/Nd₂O₃ Ba/Nd₂O₃ B/Nd₂O₃ P/Nd₂O₃ Sm₂O₃ Sr/Sm₂O₃ Ba/Sm₂O₃ B/Sm₂O₃ P/Sm₂O₃ Eu₂O₃ Sr/Eu₂O₃ Ba/Eu₂O₃ B/Eu₂O₃ P/Eu₂O₃ Gd₂O₃ Sr/Gd₂O₃ Ba/Gd₂O₃ B/Gd₂O₃ P/Gd₂O₃ Tb₂O₃ Sr/Tb₂O₃ Ba/Tb₂O₃ B/Tb₂O₃ P/Tb₂O₃ TbO₂ Sr/TbO₂ Ba/TbO₂ B/TbO₂ P/TbO₂ Tb₆O₁₁ Sr/Tb₆O₁₁ Ba/Tb₆O₁₁ B/Tb₆O₁₁ P/Tb₆O₁₁ Dy₂O₃ Sr/Dy₂O₃ Ba/Dy₂O₃ B/Dy₂O₃ P/Dy₂O₃ Ho₂O₃ Sr/Ho₂O₃ Ba/Ho₂O₃ B/Ho₂O₃ P/Ho₂O₃ Er₂O₃ Sr/Er₂O₃ Ba/Er₂O₃ B/Er₂O₃ P/Er₂O₃ Tm₂O₃ Sr/Tm₂O₃ Ba/Tm₂O₃ B/Tm₂O₃ P/Tm₂O₃ Yb₂O₃ Sr/Yb₂O₃ Ba/Yb₂O₃ B/Yb₂O₃ P/Yb₂O₃ Lu₂O₃ Sr/Lu₂O₃ Ba/Lu₂O₃ B/Lu₂O₃ P/Lu₂O₃ Ac₂O₃ Sr/Ac₂O₃ Ba/Ac₂O₃ B/Ac₂O₃ P/Ac₂O₃ Th₂O₃ Sr/Th₂O₃ Ba/Th₂O₃ B/Th₂O₃ P/Th₂O₃ ThO₂ Sr/ThO₂ Ba/ThO₂ B/ThO₂ P/ThO₂ Pa₂O₃ Sr/Pa₂O₃ Ba/Pa₂O₃ B/Pa₂O₃ P/Pa₂O₃ PaO₂ Sr/PaO₂ Ba/PaO₂ B/PaO₂ P/PaO₂ TiO₂ Sr/TiO₂ Ba/TiO₂ B/TiO₂ P/TiO₂ TiO Sr/TiO Ba/TiO B/TiO P/TiO Ti₂O₃ Sr/Ti₂O₃ Ba/Ti₂O₃ B/Ti₂O₃ P/Ti₂O₃ Ti₃O Sr/Ti₃O Ba/Ti₃O B/Ti₃O P/Ti₃O Ti₂O Sr/Ti₂O Ba/Ti₂O B/Ti₂O P/Ti₂O Ti₃O₅ Sr/Ti₃O₅ Ba/Ti₃O₅ B/Ti₃O₅ P/Ti₃O₅ Ti₄O₇ Sr/Ti₄O₇ Ba/Ti₄O₇ B/Ti₄O₇ P/Ti₄O₇ ZrO₂ Sr/ZrO₂ Ba/ZrO₂ B/ZrO₂ P/ZrO₂ HfO₂ Sr/HfO₂ Ba/HfO₂ B/HfO₂ P/HfO₂ VO Sr/VO Ba/VO B/VO P/VO V₂O₃ Sr/V₂O₃ Ba/V₂O₃ B/V₂O₃ P/V₂O₃ VO₂ Sr/VO₂ Ba/VO₂ B/VO₂ P/VO₂ V₂O₅ Sr/V₂O₅ Ba/V₂O₅ B/V₂O₅ P/V₂O₅ V₃O₇ Sr/V₃O₇ Ba/V₃O₇ B/V₃O₇ P/V₃O₇ V₄O₉ Sr/V₄O₉ Ba/V₄O₉ B/V₄O₉ P/V₄O₉ V₆O₁₃ Sr/V₆O₁₃ Ba/V₆O₁₃ B/V₆O₁₃ P/V₆O₁₃ NbO Sr/NbO Ba/NbO B/NbO P/NbO NbO₂ Sr/NbO₂ Ba/NbO₂ B/NbO₂ P/NbO₂ Nb₂O₅ Sr/Nb₂O₅ Ba/Nb₂O₅ B/Nb₂O₅ P/Nb₂O₅ Nb₈O₁₉ Sr/Nb₈O₁₉ Ba/Nb₈O₁₉ B/Nb₈O₁₉ P/Nb₈O₁₉ Nb₁₆O₃₈ Sr/Nb₁₆O₃₈ Ba/Nb₁₆O₃₈ B/Nb₁₆O₃₈ P/Nb₁₆O₃₈ Nb₁₂O₂₉ Sr/Nb₁₂O₂₉ Ba/Nb₁₂O₂₉ B/Nb₁₂O₂₉ P/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Sr/Nb₄₇O₁₁₆ Ba/Nb₄₇O₁₁₆ B/Nb₄₇O₁₁₆ P/Nb₄₇O₁₁₆ Ta₂O₅ Sr/Ta₂O₅ Ba/Ta₂O₅ B/Ta₂O₅ P/Ta₂O₅ CrO Sr/CrO Ba/CrO B/CrO P/CrO Cr₂O₃ Sr/Cr₂O₃ Ba/Cr₂O₃ B/Cr₂O₃ P/Cr₂O₃ CrO₂ Sr/CrO₂ Ba/CrO₂ B/CrO₂ P/CrO₂ CrO₃ Sr/CrO₃ Ba/CrO₃ B/CrO₃ P/CrO₃ Cr₈O₂₁ Sr/Cr₈O₂₁ Ba/Cr₈O₂₁ B/Cr₈O₂₁ P/Cr₈O₂₁ MoO₂ Sr/MoO₂ Ba/MoO₂ B/MoO₂ P/MoO₂ MoO₃ Sr/MoO₃ Ba/MoO₃ B/MoO₃ P/MoO₃ W₂O₃ Sr/W₂O₃ Ba/W₂O₃ B/W₂O₃ P/W₂O₃ WoO₂ Sr/WoO₂ Ba/WoO₂ B/WoO₂ P/WoO₂ WoO₃ Sr/WoO₃ Ba/WoO₃ B/WoO₃ P/WoO₃ MnO Sr/MnO Ba/MnO B/MnO P/MnO Mn/Mg/O Sr/Mn/Mg/O Ba/Mn/Mg/O B/Mn/Mg/O P/Mn/Mg/O Mn₃O₄ Sr/Mn₃O₄ Ba/Mn₃O₄ B/Mn₃O₄ P/Mn₃O₄ Mn₂O₃ Sr/Mn₂O₃ Ba/Mn₂O₃ B/Mn₂O₃ P/Mn₂O₃ MnO₂ Sr/MnO₂ Ba/MnO₂ B/MnO₂ P/MnO₂ Mn₂O₇ Sr/Mn₂O₇ Ba/Mn₂O₇ B/Mn₂O₇ P/Mn₂O₇ ReO₂ Sr/ReO₂ Ba/ReO₂ B/ReO₂ P/ReO₂ ReO₃ Sr/ReO₃ Ba/ReO₃ B/ReO₃ P/ReO₃ Re₂O₇ Sr/Re₂O₇ Ba/Re₂O₇ B/Re₂O₇ P/Re₂O₇ Mg₃Mn₃— B₂O₁₀ Sr/Mg₃Mn₃— B₂O₁₀ Ba/Mg₃Mn₃— B₂O₁₀ B/Mg₃Mn₃— B₂O₁₀ P/Mg₃Mn₃— B₂O₁₀ Mg₃(BO₃)₂ Sr/Mg₃(BO₃)₂ Ba/Mg₃(BO₃)₂ B/Mg₃(BO₃)₂ P/Mg₃(BO₃)₂ NaWO₄ Sr/NaWO₄ Ba/NaWO₄ B/NaWO₄ P/NaWO₄ Mg₆MnO₈ Sr/Mg₆MnO₈ Ba/Mg₆MnO₈ B/Mg₆MnO₈ P/Mg₆MnO₈ (Li,Mg)₆MnO₈ Sr/(Li,Mg)₆MnO₈ Ba/(Li,Mg)₆MnO₈ B/(Li,Mg)₆MnO₈ P/(Li,Mg)₆MnO₈ Mn₂O₄ Sr/Mn₂O₄ Ba/Mn₂O₄ B/Mn₂O₄ P/Mn₂O₄ Na₄P₂O₇ Sr/Na₄P₂O₇ Ba/Na₄P₂O₇ B/Na₄P₂O₇ P/Na₄P₂O₇ Mo₂O₈ Sr/Mo₂O₈ Ba/Mo₂O₈ B/Mo₂O₈ P/Mo₂O₈ Mn₃O₄/WO₄ Sr/Mn₃O₄/WO₄ Ba/Mn₃O₄/WO₄ B/Mn₃O₄/WO₄ P/Mn₃O₄/WO₄ Na₂WO₄ Sr/Na₂WO₄ Ba/Na₂WO₄ B/Na₂WO₄ P/Na₂WO₄ Zr₂Mo₂O₈ Sr/Zr₂Mo₂O₈ Ba/Zr₂Mo₂O₈ B/Zr₂Mo₂O₈ P/Zr₂Mo₂O₈ NaMnO₄/MgO Sr/NaMnO₄/MgO Ba/NaMnO₄/MgO B/NaMnO₄/MgO P/NaMnO₄/MgO Na₁₀Mn— W₅O₁₇ Sr/Na₁₀Mn— W₅O₁₇ Ba/Na₁₀Mn— W₅O₁₇ B/Na₁₀Mn— W₅O₁₇ P/Na₁₀Mn— W₅O₁₇ NW\Dop S F Cl Li₂O S/Li₂O F/Li₂O Cl/Li₂O Na₂O S/Na₂O F/Na₂O Cl/Na₂O K₂O S/K₂O F/K₂O Cl/K₂O Rb₂O S/Rb₂O F/Rb₂O Cl/Rb₂O Cs₂O S/Cs₂O F/Cs₂O Cl/Cs₂O BeO S/BeO F/BeO Cl/BeO MgO S/MgO F/MgO Cl/MgO CaO S/CaO F/CaO Cl/CaO SrO S/SrO F/SrO Cl/SrO BaO S/BaO F/BaO Cl/BaO Sc₂O₃ S/Sc₂O₃ F/Sc₂O₃ Cl/Sc₂O₃ Y₂O₃ S/Y₂O₃ F/Y₂O₃ Cl/Y₂O₃ La₂O₃ S/La₂O₃ F/La₂O₃ Cl/La₂O₃ CeO₂ S/CeO₂ F/CeO₂ Cl/CeO₂ Ce₂O₃ S/Ce₂O₃ F/Ce₂O₃ Cl/Ce₂O₃ Pr₂O₃ S/Pr₂O₃ F/Pr₂O₃ Cl/Pr₂O₃ Nd₂O₃ S/Nd₂O₃ F/Nd₂O₃ Cl/Nd₂O₃ Sm₂O₃ S/Sm₂O₃ F/Sm₂O₃ Cl/Sm₂O₃ Eu₂O₃ S/Eu₂O₃ F/Eu₂O₃ Cl/Eu₂O₃ Gd₂O₃ S/Gd₂O₃ F/Gd₂O₃ Cl/Gd₂O₃ Tb₂O₃ S/Tb₂O₃ F/Tb₂O₃ Cl/Tb₂O₃ TbO₂ S/TbO₂ F/TbO₂ Cl/TbO₂ Tb₆O₁₁ S/Tb₆O₁₁ F/Tb₆O₁₁ Cl/Tb₆O₁₁ Dy₂O₃ S/Dy₂O₃ F/Dy₂O₃ Cl/Dy₂O₃ Ho₂O₃ S/Ho₂O₃ F/Ho₂O₃ Cl/Ho₂O₃ Er₂O₃ S/Er₂O₃ F/Er₂O₃ Cl/Er₂O₃ Tm₂O₃ S/Tm₂O₃ F/Tm₂O₃ Cl/Tm₂O₃ Yb₂O₃ S/Yb₂O₃ F/Yb₂O₃ Cl/Yb₂O₃ Lu₂O₃ S/Lu₂O₃ F/Lu₂O₃ Cl/Lu₂O₃ Ac₂O₃ S/Ac₂O₃ F/Ac₂O₃ Cl/Ac₂O₃ Th₂O₃ S/Th₂O₃ F/Th₂O₃ Cl/Th₂O₃ ThO₂ S/ThO₂ F/ThO₂ Cl/ThO₂ Pa₂O₃ S/Pa₂O₃ F/Pa₂O₃ Cl/Pa₂O₃ PaO₂ S/PaO₂ F/PaO₂ Cl/PaO₂ TiO₂ S/TiO₂ F/TiO₂ Cl/TiO₂ TiO S/TiO F/TiO Cl/TiO Ti₂O₃ S/Ti₂O₃ F/Ti₂O₃ Cl/Ti₂O₃ Ti₃O S/Ti₃O F/Ti₃O Cl/Ti₃O Ti₂O S/Ti₂O F/Ti₂O Cl/Ti₂O Ti₃O₅ S/Ti₃O₅ F/Ti₃O₅ Cl/Ti₃O₅ Ti₄O₇ S/Ti₄O₇ F/Ti₄O₇ Cl/Ti₄O₇ ZrO₂ S/ZrO₂ F/ZrO₂ Cl/ZrO₂ HfO₂ S/HfO₂ F/HfO₂ Cl/HfO₂ VO S/VO F/VO Cl/VO V₂O₃ S/V₂O₃ F/V₂O₃ Cl/V₂O₃ VO₂ S/VO₂ F/VO₂ Cl/VO₂ V₂O₅ S/V₂O₅ F/V₂O₅ Cl/V₂O₅ V₃O₇ S/V₃O₇ F/V₃O₇ Cl/V₃O₇ V₄O₉ S/V₄O₉ F/V₄O₉ Cl/V₄O₉ V₆O₁₃ S/V₆O₁₃ F/V₆O₁₃ Cl/V₆O₁₃ NbO S/NbO F/NbO Cl/NbO NbO₂ S/NbO₂ F/NbO₂ Cl/NbO₂ Nb₂O₅ S/Nb₂O₅ F/Nb₂O₅ Cl/Nb₂O₅ Nb₈O₁₉ S/Nb₈O₁₉ F/Nb₈O₁₉ Cl/Nb₈O₁₉ Nb₁₆O₃₈ S/Nb₁₆O₃₈ F/Nb₁₆O₃₈ Cl/Nb₁₆O₃₈ Nb₁₂O₂₉ S/Nb₁₂O₂₉ F/Nb₁₂O₂₉ Cl/Nb₁₂O₂₉ Nb₄₇O₁₁₆ S/Nb₄₇O₁₁₆ F/Nb₄₇O₁₁₆ Cl/Nb₄₇O₁₁₆ Ta₂O₅ S/Ta₂O₅ F/Ta₂O₅ Cl/Ta₂O₅ CrO S/CrO F/CrO Cl/CrO Cr₂O₃ S/Cr₂O₃ F/Cr₂O₃ Cl/Cr₂O₃ CrO₂ S/CrO₂ F/CrO₂ Cl/CrO₂ CrO₃ S/CrO₃ F/CrO₃ Cl/CrO₃ Cr₈O₂₁ S/Cr₈O₂₁ F/Cr₈O₂₁ Cl/Cr₈O₂₁ MoO₂ S/MoO₂ F/MoO₂ Cl/MoO₂ MoO₃ S/MoO₃ F/MoO₃ Cl/MoO₃ W₂O₃ S/W₂O₃ F/W₂O₃ Cl/W₂O₃ WoO₂ S/WoO₂ F/WoO₂ Cl/WoO₂ WoO₃ S/WoO₃ F/WoO₃ Cl/WoO₃ MnO S/MnO F/MnO Cl/MnO Mn/Mg/O S/Mn/Mg/O F/Mn/Mg/O Cl/Mn/Mg/O Mn₃O₄ S/Mn₃O₄ F/Mn₃O₄ Cl/Mn₃O₄ Mn₂O₃ S/Mn₂O₃ F/Mn₂O₃ Cl/Mn₂O₃ MnO₂ S/MnO₂ F/MnO₂ Cl/MnO₂ Mn₂O₇ S/Mn₂O₇ F/Mn₂O₇ Cl/Mn₂O₇ ReO₂ S/ReO₂ F/ReO₂ Cl/ReO₂ ReO₃ S/ReO₃ F/ReO₃ Cl/ReO₃ Re₂O₇ S/Re₂O₇ F/Re₂O₇ Cl/Re₂O₇ Mg₃Mn₃— B₂O₁₀ S/Mg₃Mn₃— B₂O₁₀ F/Mg₃Mn₃— B₂O₁₀ Cl/Mg₃Mn₃— B₂O₁₀ Mg₃(BO₃)₂ S/Mg₃(BO₃)₂ F/Mg₃(BO₃)₂ Cl/Mg₃(BO₃)₂ NaWO₄ S/NaWO₄ F/NaWO₄ Cl/NaWO₄ Mg₆MnO₈ S/Mg₆MnO₈ F/Mg₆MnO₈ Cl/Mg₆MnO₈ (Li,Mg)₆MnO₈ S/(Li,Mg)₆MnO₈ F/(Li,Mg)₆MnO₈ Cl/(Li,Mg)₆MnO₈ Mn₂O₄ S/Mn₂O₄ F/Mn₂O₄ Cl/Mn₂O₄ Na₄P₂O₇ S/Na₄P₂O₇ F/Na₄P₂O₇ Cl/Na₄P₂O₇ Mo₂O₈ S/Mo₂O₈ F/Mo₂O₈ Cl/Mo₂O₈ Mn₃O₄/WO₄ S/Mn₃O₄/WO₄ F/Mn₃O₄/WO₄ Cl/Mn₃O₄/WO₄ Na₂WO₄ S/Na₂WO₄ F/Na₂WO₄ Cl/Na₂WO₄ Zr₂Mo₂O₈ S/Zr₂Mo₂O₈ F/Zr₂Mo₂O₈ Cl/Zr₂Mo₂O₈ NaMnO₄/MgO S/NaMnO₄/MgO F/NaMnO₄/MgO Cl/NaMnO₄/MgO Na₁₀Mn— W₅O₁₇ S/Na₁₀Mn— W₅O₁₇ F/Na₁₀Mn— W₅O₁₇ Cl/Na₁₀Mn— W₅O₁₇

TABLE 3 NANOWIRES (NW) DOPED WITH SPECIFIC DOPANTS (DOP) NW\Dop La Ce Pr Nd Li₂O La/Li₂O Ce/Li₂O Pr/Li₂O Nd/Li₂O Na₂O La/Na₂O Ce/Na₂O Pr/Na₂O Nd/Na₂O K₂O La/K₂O Ce/K₂O Pr/K₂O Nd/K₂O Rb₂O La/Rb₂O Ce/Rb₂O Pr/Rb₂O Nd/Rb₂O Cs₂O La/Cs₂O Ce/Cs₂O Pr/Cs₂O Nd/Cs₂O BeO La/BeO Ce/BeO Pr/BeO Nd/BeO MgO La/MgO Ce/MgO Pr/MgO Nd/MgO CaO La/CaO Ce/CaO Pr/CaO Nd/CaO SrO La/SrO Ce/SrO Pr/SrO Nd/SrO BaO La/BaO Ce/BaO Pr/BaO Nd/BaO Sc₂O₃ La/Sc₂O₃ Ce/Sc₂O₃ Pr/Sc₂O₃ Nd/Sc₂O₃ Y₂O₃ La/Y₂O₃ Ce/Y₂O₃ Pr/Y₂O₃ Nd/Y₂O₃ La₂O₃ La/La₂O₃ Ce/La₂O₃ Pr/La₂O₃ Nd/La₂O₃ CeO₂ La/CeO₂ Ce/CeO₂ Pr/CeO₂ Nd/CeO₂ Ce₂O₃ La/Ce₂O₃ Ce/Ce₂O₃ Pr/Ce₂O₃ Nd/Ce₂O₃ Pr₂O₃ La/Pr₂O₃ Ce/Pr₂O₃ Pr/Pr₂O₃ Nd/Pr₂O₃ Nd₂O₃ La/Nd₂O₃ Ce/Nd₂O₃ Pr/Nd₂O₃ Nd/Nd₂O₃ Sm₂O₃ La/Sm₂O₃ Ce/Sm₂O₃ Pr/Sm₂O₃ Nd/Sm₂O₃ Eu₂O₃ La/Eu₂O₃ Ce/Eu₂O₃ Pr/Eu₂O₃ Nd/Eu₂O₃ Gd₂O₃ La/Gd₂O₃ Ce/Gd₂O₃ Pr/Gd₂O₃ Nd/Gd₂O₃ Tb₂O₃ La/Tb₂O₃ Ce/Tb₂O₃ Pr/Tb₂O₃ Nd/Tb₂O₃ TbO₂ La/TbO₂ Ce/TbO₂ Pr/TbO₂ Nd/TbO₂ Tb₆O₁₁ La/Tb₆O₁₁ Ce/Tb₆O₁₁ Pr/Tb₆O₁₁ Nd/Tb₆O₁₁ Dy₂O₃ La/Dy₂O₃ Ce/Dy₂O₃ Pr/Dy₂O₃ Nd/Dy₂O₃ Ho₂O₃ La/Ho₂O₃ Ce/Ho₂O₃ Pr/Ho₂O₃ Nd/Ho₂O₃ Er₂O₃ La/Er₂O₃ Ce/Er₂O₃ Pr/Er₂O₃ Nd/Er₂O₃ Tm₂O₃ La/Tm₂O₃ Ce/Tm₂O₃ Pr/Tm₂O₃ Nd/Tm₂O₃ Yb₂O₃ La/Yb₂O₃ Ce/Yb₂O₃ Pr/Yb₂O₃ Nd/Yb₂O₃ Lu₂O₃ La/Lu₂O₃ Ce/Lu₂O₃ Pr/Lu₂O₃ Nd/Lu₂O₃ Ac₂O₃ La/Ac₂O₃ Ce/Ac₂O₃ Pr/Ac₂O₃ Nd/Ac₂O₃ Th₂O₃ La/Th₂O₃ Ce/Th₂O₃ Pr/Th₂O₃ Nd/Th₂O₃ ThO₂ La/ThO₂ Ce/ThO₂ Pr/ThO₂ Nd/ThO₂ Pa₂O₃ La/Pa₂O₃ Ce/Pa₂O₃ Pr/Pa₂O₃ Nd/Pa₂O₃ PaO₂ La/PaO₂ Ce/PaO₂ Pr/PaO₂ Nd/PaO₂ TiO₂ La/TiO₂ Ce/TiO₂ Pr/TiO₂ Nd/TiO₂ TiO La/TiO Ce/TiO Pr/TiO Nd/TiO Ti₂O₃ La/Ti₂O₃ Ce/Ti₂O₃ Pr/Ti₂O₃ Nd/Ti₂O₃ Ti₃O La/Ti₃O Ce/Ti₃O Pr/Ti₃O Nd/Ti₃O Ti₂O La/Ti₂O Ce/Ti₂O Pr/Ti₂O Nd/Ti₂O Ti₃O₅ La/Ti₃O₅ Ce/Ti₃O₅ Pr/Ti₃O₅ Nd/Ti₃O₅ Ti₄O₇ La/Ti₄O₇ Ce/Ti₄O₇ Pr/Ti₄O₇ Nd/Ti₄O₇ ZrO₂ La/ZrO₂ Ce/ZrO₂ Pr/ZrO₂ Nd/ZrO₂ HfO₂ La/HfO₂ Ce/HfO₂ Pr/HfO₂ Nd/HfO₂ VO La/VO Ce/VO Pr/VO Nd/VO V₂O₃ La/V₂O₃ Ce/V₂O₃ Pr/V₂O₃ Nd/V₂O₃ VO₂ La/VO₂ Ce/VO₂ Pr/VO₂ Nd/VO₂ V₂O₅ La/V₂O₅ Ce/V₂O₅ Pr/V₂O₅ Nd/V₂O₅ V₃O₇ La/V₃O₇ Ce/V₃O₇ Pr/V₃O₇ Nd/V₃O₇ V₄O₉ La/V₄O₉ Ce/V₄O₉ Pr/V₄O₉ Nd/V₄O₉ V₆O₁₃ La/V₆O₁₃ Ce/V₆O₁₃ Pr/V₆O₁₃ Nd/V₆O₁₃ NbO La/NbO Ce/NbO Pr/NbO Nd/NbO NbO₂ La/NbO₂ Ce/NbO₂ Pr/NbO₂ Nd/NbO₂ Nb₂O₅ La/Nb₂O₅ Ce/Nb₂O₅ Pr/Nb₂O₅ Nd/Nb₂O₅ Nb₈O₁₉ La/Nb₈O₁₉ Ce/Nb₈O₁₉ Pr/Nb₈O₁₉ Nd/Nb₈O₁₉ Nb₁₆O₃₈ La/Nb₁₆O₃₈ Ce/Nb₁₆O₃₈ Pr/Nb₁₆O₃₈ Nd/Nb₁₆O₃₈ Nb₁₂O₂₉ La/Nb₁₂O₂₉ Ce/Nb₁₂O₂₉ Pr/Nb₁₂O₂₉ Nd/Nb₁₂O₂₉ Nb₄₇O₁₁₆ La/Nb₄₇O₁₁₆ Ce/Nb₄₇O₁₁₆ Pr/Nb₄₇O₁₁₆ Nd/Nb₄₇O₁₁₆ Ta₂O₅ La/Ta₂O₅ Ce/Ta₂O₅ Pr/Ta₂O₅ Nd/Ta₂O₅ CrO La/CrO Ce/CrO Pr/CrO Nd/CrO Cr₂O₃ La/Cr₂O₃ Ce/Cr₂O₃ Pr/Cr₂O₃ Nd/Cr₂O₃ CrO₂ La/CrO₂ Ce/CrO₂ Pr/CrO₂ Nd/CrO₂ CrO₃ La/CrO₃ Ce/CrO₃ Pr/CrO₃ Nd/CrO₃ Cr₈O₂₁ La/Cr₈O₂₁ Ce/Cr₈O₂₁ Pr/Cr₈O₂₁ Nd/Cr₈O₂₁ MoO₂ La/MoO₂ Ce/MoO₂ Pr/MoO₂ Nd/MoO₂ MoO₃ La/MoO₃ Ce/MoO₃ Pr/MoO₃ Nd/MoO₃ W₂O₃ La/W₂O₃ Ce/W₂O₃ Pr/W₂O₃ Nd/W₂O₃ WoO₂ La/WoO₂ Ce/WoO₂ Pr/WoO₂ Nd/WoO₂ WoO₃ La/WoO₃ Ce/WoO₃ Pr/WoO₃ Nd/WoO₃ MnO La/MnO Ce/MnO Pr/MnO Nd/MnO Mn/Mg/O La/Mn/Mg/O Ce/Mn/Mg/O Pr/Mn/Mg/O Nd/Mn/Mg/O Mn₃O₄ La/Mn₃O₄ Ce/Mn₃O₄ Pr/Mn₃O₄ Nd/Mn₃O₄ Mn₂O₃ La/Mn₂O₃ Ce/Mn₂O₃ Pr/Mn₂O₃ Nd/Mn₂O₃ MnO₂ La/MnO₂ Ce/MnO₂ Pr/MnO₂ Nd/MnO₂ Mn₂O₇ La/Mn₂O₇ Ce/Mn₂O₇ Pr/Mn₂O₇ Nd/Mn₂O₇ ReO₂ La/ReO₂ Ce/ReO₂ Pr/ReO₂ Nd/ReO₂ ReO₃ La/ReO₃ Ce/ReO₃ Pr/ReO₃ Nd/ReO₃ Re₂O₇ La/Re₂O₇ Ce/Re₂O₇ Pr/Re₂O₇ Nd/Re₂O₇ Mg₃Mn₃— B₂O₁₀ La/Mg₃Mn₃— B₂O₁₀ Ce/Mg₃Mn₃— B₂O₁₀ Pr/Mg₃Mn₃— B₂O₁₀ Nd/Mg₃Mn₃— B₂O₁₀ Mg₃(BO₃)₂ La/Mg₃(BO₃)₂ Ce/Mg₃(BO₃)₂ Pr/Mg₃(BO₃)₂ Nd/Mg₃(BO₃)₂ NaWO₄ La/NaWO₄ Ce/NaWO₄ Pr/NaWO₄ Nd/NaWO₄ Mg₆MnO₈ La/Mg₆MnO₈ Ce/Mg₆MnO₈ Pr/Mg₆MnO₈ Nd/Mg₆MnO₈ (Li,Mg)₆MnO₈ La/(Li,Mg)₆MnO₈ Ce/(Li,Mg)₆MnO₈ Pr/(Li,Mg)₆MnO₈ Nd/(Li,Mg)₆MnO₈ Mn₂O₄ La/Mn₂O₄ Ce/Mn₂O₄ Pr/Mn₂O₄ Nd/Mn₂O₄ Na₄P₂O₇ La/Na₄P₂O₇ Ce/Na₄P₂O₇ Pr/Na₄P₂O₇ Nd/Na₄P₂O₇ Mo₂O₈ La/Mo₂O₈ Ce/Mo₂O₈ Pr/Mo₂O₈ Nd/Mo₂O₈ Mn₃O₄/WO₄ La/Mn₃O₄/WO₄ Ce/Mn₃O₄/WO₄ Pr/Mn₃O₄/WO₄ Nd/Mn₃O₄/WO₄ Na₂WO₄ La/Na₂WO₄ Ce/Na₂WO₄ Pr/Na₂WO₄ Nd/Na₂WO₄ Zr₂Mo₂O₈ La/Zr₂Mo₂O₈ Ce/Zr₂Mo₂O₈ Pr/Zr₂Mo₂O₈ Nd/Zr₂Mo₂O₈ NaMnO₄—/MgO La/NaMnO₄—/MgO Ce/NaMnO₄—/MgO Pr/NaMnO₄—/MgO Nd/NaMnO₄—/MgO Na₁₀Mn— W₅O₁₇ La/Na₁₀Mn— W₅O₁₇ Ce/Na₁₀Mn— W₅O₁₇ Pr/Na₁₀Mn— W₅O₁₇ Nd/Na₁₀Mn— W₅O₁₇ NW\Dop Pm Sm Eu Gd Li₂O Pm/Li₂O Sm/Li₂O Eu/Li₂O Gd/Li₂O Na₂O Pm/Na₂O Sm/Na₂O Eu/Na₂O Gd/Na₂O K₂O Pm/K₂O Sm/K₂O Eu/K₂O Gd/K₂O Rb₂O Pm/Rb₂O Sm/Rb₂O Eu/Rb₂O Gd/Rb₂O Cs₂O Pm/Cs₂O Sm/Cs₂O Eu/Cs₂O Gd/Cs₂O BeO Pm/BeO Sm/BeO Eu/BeO Gd/BeO MgO Pm/MgO Sm/MgO Eu/MgO Gd/MgO CaO Pm/CaO Sm/CaO Eu/CaO Gd/CaO SrO Pm/SrO Sm/SrO Eu/SrO Gd/SrO BaO Pm/BaO Sm/BaO Eu/BaO Gd/BaO Sc₂O₃ Pm/Sc₂O₃ Sm/Sc₂O₃ Eu/Sc₂O₃ Gd/Sc₂O₃ Y₂O₃ Pm/Y₂O₃ Sm/Y₂O₃ Eu/Y₂O₃ Gd/Y₂O₃ La₂O₃ Pm/La₂O₃ Sm/La₂O₃ Eu/La₂O₃ Gd/La₂O₃ CeO₂ Pm/CeO₂ Sm/CeO₂ Eu/CeO₂ Gd/CeO₂ Ce₂O₃ Pm/Ce₂O₃ Sm/Ce₂O₃ Eu/Ce₂O₃ Gd/Ce₂O₃ Pr₂O₃ Pm/Pr₂O₃ Sm/Pr₂O₃ Eu/Pr₂O₃ Gd/Pr₂O₃ Nd₂O₃ Pm/Nd₂O₃ Sm/Nd₂O₃ Eu/Nd₂O₃ Gd/Nd₂O₃ Sm₂O₃ Pm/Sm₂O₃ Sm/Sm₂O₃ Eu/Sm₂O₃ Gd/Sm₂O₃ Eu₂O₃ Pm/Eu₂O₃ Sm/Eu₂O₃ Eu/Eu₂O₃ Gd/Eu₂O₃ Gd₂O₃ Pm/Gd₂O₃ Sm/Gd₂O₃ Eu/Gd₂O₃ Gd/Gd₂O₃ Tb₂O₃ Pm/Tb₂O₃ Sm/Tb₂O₃ Eu/Tb₂O₃ Gd/Tb₂O₃ TbO₂ Pm/TbO₂ Sm/TbO₂ Eu/TbO₂ Gd/TbO₂ Tb₆O₁₁ Pm/Tb₆O₁₁ Sm/Tb₆O₁₁ Eu/Tb₆O₁₁ Gd/Tb₆O₁₁ Dy₂O₃ Pm/Dy₂O₃ Sm/Dy₂O₃ Eu/Dy₂O₃ Gd/Dy₂O₃ Ho₂O₃ Pm/Ho₂O₃ Sm/Ho₂O₃ Eu/Ho₂O₃ Gd/Ho₂O₃ Er₂O₃ Pm/Er₂O₃ Sm/Er₂O₃ Eu/Er₂O₃ Gd/Er₂O₃ Tm₂O₃ Pm/Tm₂O₃ Sm/Tm₂O₃ Eu/Tm₂O₃ Gd/Tm₂O₃ Yb₂O₃ Pm/Yb₂O₃ Sm/Yb₂O₃ Eu/Yb₂O₃ Gd/Yb₂O₃ Lu₂O₃ Pm/Lu₂O₃ Sm/Lu₂O₃ Eu/Lu₂O₃ Gd/Lu₂O₃ Ac₂O₃ Pm/Ac₂O₃ Sm/Ac₂O₃ Eu/Ac₂O₃ Gd/Ac₂O₃ Th₂O₃ Pm/Th₂O₃ Sm/Th₂O₃ Eu/Th₂O₃ Gd/Th₂O₃ ThO₂ Pm/ThO₂ Sm/ThO₂ Eu/ThO₂ Gd/ThO₂ Pa₂O₃ Pm/Pa₂O₃ Sm/Pa₂O₃ Eu/Pa₂O₃ Gd/Pa₂O₃ PaO₂ Pm/PaO₂ Sm/PaO₂ Eu/PaO₂ Gd/PaO₂ TiO₂ Pm/TiO₂ Sm/TiO₂ Eu/TiO₂ Gd/TiO₂ TiO Pm/TiO Sm/TiO Eu/TiO Gd/TiO Ti₂O₃ Pm/Ti₂O₃ Sm/Ti₂O₃ Eu/Ti₂O₃ Gd/Ti₂O₃ Ti₃O Pm/Ti₃O Sm/Ti₃O Eu/Ti₃O Gd/Ti₃O Ti₂O Pm/Ti₂O Sm/Ti₂O Eu/Ti₂O Gd/Ti₂O Ti₃O₅ Pm/Ti₃O₅ Sm/Ti₃O₅ Eu/Ti₃O₅ Gd/Ti₃O₅ Ti₄O₇ Pm/Ti₄O₇ Sm/Ti₄O₇ Eu/Ti₄O₇ Gd/Ti₄O₇ ZrO₂ Pm/ZrO₂ Sm/ZrO₂ Eu/ZrO₂ Gd/ZrO₂ HfO₂ Pm/HfO₂ Sm/HfO₂ Eu/HfO₂ Gd/HfO₂ VO Pm/VO Sm/VO Eu/VO Gd/VO V₂O₃ Pm/V₂O₃ Sm/V₂O₃ Eu/V₂O₃ Gd/V₂O₃ VO₂ Pm/VO₂ Sm/VO₂ Eu/VO₂ Gd/VO₂ V₂O₅ Pm/V₂O₅ Sm/V₂O₅ Eu/V₂O₅ Gd/V₂O₅ V₃O₇ Pm/V₃O₇ Sm/V₃O₇ Eu/V₃O₇ Gd/V₃O₇ V₄O₉ Pm/V₄O₉ Sm/V₄O₉ Eu/V₄O₉ Gd/V₄O₉ V₆O₁₃ Pm/V₆O₁₃ Sm/V₆O₁₃ Eu/V₆O₁₃ Gd/V₆O₁₃ NbO Pm/NbO Sm/NbO Eu/NbO Gd/NbO NbO₂ Pm/NbO₂ Sm/NbO₂ Eu/NbO₂ Gd/NbO₂ Nb₂O₅ Pm/Nb₂O₅ Sm/Nb₂O₅ Eu/Nb₂O₅ Gd/Nb₂O₅ Nb₈O₁₉ Pm/Nb₈O₁₉ Sm/Nb₈O₁₉ Eu/Nb₈O₁₉ Gd/Nb₈O₁₉ Nb₁₆O₃₈ Pm/Nb₁₆O₃₈ Sm/Nb₁₆O₃₈ Eu/Nb₁₆O₃₈ Gd/Nb₁₆O₃₈ Nb₁₂O₂₉ Pm/Nb₁₂O₂₉ Sm/Nb₁₂O₂₉ Eu/Nb₁₂O₂₉ Gd/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Pm/Nb₄₇O₁₁₆ Sm/Nb₄₇O₁₁₆ Eu/Nb₄₇O₁₁₆ Gd/Nb₄₇O₁₁₆ Ta₂O₅ Pm/Ta₂O₅ Sm/Ta₂O₅ Eu/Ta₂O₅ Gd/Ta₂O₅ CrO Pm/CrO Sm/CrO Eu/CrO Gd/CrO Cr₂O₃ Pm/Cr₂O₃ Sm/Cr₂O₃ Eu/Cr₂O₃ Gd/Cr₂O₃ CrO₂ Pm/CrO₂ Sm/CrO₂ Eu/CrO₂ Gd/CrO₂ CrO₃ Pm/CrO₃ Sm/CrO₃ Eu/CrO₃ Gd/CrO₃ Cr₈O₂₁ Pm/Cr₈O₂₁ Sm/Cr₈O₂₁ Eu/Cr₈O₂₁ Gd/Cr₈O₂₁ MoO₂ Pm/MoO₂ Sm/MoO₂ Eu/MoO₂ Gd/MoO₂ MoO₃ Pm/MoO₃ Sm/MoO₃ Eu/MoO₃ Gd/MoO₃ W₂O₃ Pm/W₂O₃ Sm/W₂O₃ Eu/W₂O₃ Gd/W₂O₃ WoO₂ Pm/WoO₂ Sm/WoO₂ Eu/WoO₂ Gd/WoO₂ WoO₃ Pm/WoO₃ Sm/WoO₃ Eu/WoO₃ Gd/WoO₃ MnO Pm/MnO Sm/MnO Eu/MnO Gd/MnO Mn/Mg/O Pm/Mn/Mg/O Sm/Mn/Mg/O Eu/Mn/Mg/O Gd/Mn/Mg/O Mn₃O₄ Pm/Mn₃O₄ Sm/Mn₃O₄ Eu/Mn₃O₄ Gd/Mn₃O₄ Mn₂O₃ Pm/Mn₂O₃ Sm/Mn₂O₃ Eu/Mn₂O₃ Gd/Mn₂O₃ MnO₂ Pm/MnO₂ Sm/MnO₂ Eu/MnO₂ Gd/MnO₂ Mn₂O₇ Pm/Mn₂O₇ Sm/Mn₂O₇ Eu/Mn₂O₇ Gd/Mn₂O₇ ReO₂ Pm/ReO₂ Sm/ReO₂ Eu/ReO₂ Gd/ReO₂ ReO₃ Pm/ReO₃ Sm/ReO₃ Eu/ReO₃ Gd/ReO₃ Re₂O₇ Pm/Re₂O₇ Sm/Re₂O₇ Eu/Re₂O₇ Gd/Re₂O₇ Mg₃Mn₃— B₂O₁₀ Pm/Mg₃Mn₃— B₂O₁₀ Sm/Mg₃Mn₃— B₂O₁₀ Eu/Mg₃Mn₃— B₂O₁₀ Gd/Mg₃Mn₃— B₂O₁₀ Mg₃(BO₃)₂ Pm/Mg₃(BO₃)₂ Sm/Mg₃(BO₃)₂ Eu/Mg₃(BO₃)₂ Gd/Mg₃(BO₃)₂ NaWO₄ Pm/NaWO₄ Sm/NaWO₄ Eu/NaWO₄ Gd/NaWO₄ Mg₆MnO₈ Pm/Mg₆MnO₈ Sm/Mg₆MnO₈ Eu/Mg₆MnO₈ Gd/Mg₆MnO₈ (Li,Mg)₆MnO₈ Pm/(Li,Mg)₆MnO₈ Sm/(Li,Mg)₆MnO₈ Eu/(Li,Mg)₆MnO₈ Gd/(Li,Mg)₆MnO₈ Mn₂O₄ Pm/Mn₂O₄ Sm/Mn₂O₄ Eu/Mn₂O₄ Gd/Mn₂O₄ Na₄P₂O₇ Pm/Na₄P₂O₇ Sm/Na₄P₂O₇ Eu/Na₄P₂O₇ Gd/Na₄P₂O₇ Mo₂O₈ Pm/Mo₂O₈ Sm/Mo₂O₈ Eu/Mo₂O₈ Gd/Mo₂O₈ Mn₃O₄/WO₄ Pm/Mn₃O₄/WO₄ Sm/Mn₃O₄/WO₄ Eu/Mn₃O₄/WO₄ Gd/Mn₃O₄/WO₄ Na₂WO₄ Pm/Na₂WO₄ Sm/Na₂WO₄ Eu/Na₂WO₄ Gd/Na₂WO₄ Zr₂Mo₂O₈ Pm/Zr₂Mo₂O₈ Sm/Zr₂Mo₂O₈ Eu/Zr₂Mo₂O₈ Gd/Zr₂Mo₂O₈ NaMnO₄—/MgO Pm/NaMnO₄—/MgO Sm/NaMnO₄—/MgO Eu/NaMnO₄—/MgO Gd/NaMnO₄—/MgO Na₁₀Mn— W₅O₁₇ Pm/Na₁₀Mn— W₅O₁₇ Sm/Na₁₀Mn— W₅O₁₇ Eu/Na₁₀Mn— W₅O₁₇ Gd/Na₁₀Mn— W₅O₁₇

TABLE 4 NANOWIRES (NW) DOPED WITH SPECIFIC DOPANTS (DOP) NW\Dop Tb Dy Ho Er Li₂O Tb/Li₂O Dy/Li₂O Ho/Li₂O Er/Li₂O Na₂O Tb/Na₂O Dy/Na₂O Ho/Na₂O Er/Na₂O K₂O Tb/K₂O Dy/K₂O Ho/K₂O Er/K₂O Rb₂O Tb/Rb₂O Dy/Rb₂O Ho/Rb₂O Er/Rb₂O Cs₂O Tb/Cs₂O Dy/Cs₂O Ho/Cs₂O Er/Cs₂O BeO Tb/BeO Dy/BeO Ho/BeO Er/BeO MgO Tb/MgO Dy/MgO Ho/MgO Er/MgO CaO Tb/CaO Dy/CaO Ho/CaO Er/CaO SrO Tb/SrO Dy/SrO Ho/SrO Er/SrO BaO Tb/BaO Dy/BaO Ho/BaO Er/BaO Sc₂O₃ Tb/Sc₂O₃ Dy/Sc₂O₃ Ho/Sc₂O₃ Er/Sc₂O₃ Y₂O₃ Tb/Y₂O₃ Dy/Y₂O₃ Ho/Y₂O₃ Er/Y₂O₃ La₂O₃ Tb/La₂O₃ Dy/La₂O₃ Ho/La₂O₃ Er/La₂O₃ CeO₂ Tb/CeO₂ Dy/CeO₂ Ho/CeO₂ Er/CeO₂ Ce₂O₃ Tb/Ce₂O₃ Dy/Ce₂O₃ Ho/Ce₂O₃ Er/Ce₂O₃ Pr₂O₃ Tb/Pr₂O₃ Dy/Pr₂O₃ Ho/Pr₂O₃ Er/Pr₂O₃ Nd₂O₃ Tb/Nd₂O₃ Dy/Nd₂O₃ Ho/Nd₂O₃ Er/Nd₂O₃ Sm₂O₃ Tb/Sm₂O₃ Dy/Sm₂O₃ Ho/Sm₂O₃ Er/Sm₂O₃ Eu₂O₃ Tb/Eu₂O₃ Dy/Eu₂O₃ Ho/Eu₂O₃ Er/Eu₂O₃ Gd₂O₃ Tb/Gd₂O₃ Dy/Gd₂O₃ Ho/Gd₂O₃ Er/Gd₂O₃ Tb₂O₃ Tb/Tb₂O₃ Dy/Tb₂O₃ Ho/Tb₂O₃ Er/Tb₂O₃ TbO₂ Tb/TbO₂ Dy/TbO₂ Ho/TbO₂ Er/TbO₂ Tb₆O₁₁ Tb/Tb₆O₁₁ Dy/Tb₆O₁₁ Ho/Tb₆O₁₁ Er/Tb₆O₁₁ Dy₂O₃ Tb/Dy₂O₃ Dy/Dy₂O₃ Ho/Dy₂O₃ Er/Dy₂O₃ Ho₂O₃ Tb/Ho₂O₃ Dy/Ho₂O₃ Ho/Ho₂O₃ Er/Ho₂O₃ Er₂O₃ Tb/Er₂O₃ Dy/Er₂O₃ Ho/Er₂O₃ Er/Er₂O₃ Tm₂O₃ Tb/Tm₂O₃ Dy/Tm₂O₃ Ho/Tm₂O₃ Er/Tm₂O₃ Yb₂O₃ Tb/Yb₂O₃ Dy/Yb₂O₃ Ho/Yb₂O₃ Er/Yb₂O₃ Lu₂O₃ Tb/Lu₂O₃ Dy/Lu₂O₃ Ho/Lu₂O₃ Er/Lu₂O₃ Ac₂O₃ Tb/Ac₂O₃ Dy/Ac₂O₃ Ho/Ac₂O₃ Er/Ac₂O₃ Th₂O₃ Tb/Th₂O₃ Dy/Th₂O₃ Ho/Th₂O₃ Er/Th₂O₃ ThO₂ Tb/ThO₂ Dy/ThO₂ Ho/ThO₂ Er/ThO₂ Pa₂O₃ Tb/Pa₂O₃ Dy/Pa₂O₃ Ho/Pa₂O₃ Er/Pa₂O₃ PaO₂ Tb/PaO₂ Dy/PaO₂ Ho/PaO₂ Er/PaO₂ TiO₂ Tb/TiO₂ Dy/TiO₂ Ho/TiO₂ Er/TiO₂ TiO Tb/TiO Dy/TiO Ho/TiO Er/TiO Ti₂O₃ Tb/Ti₂O₃ Dy/Ti₂O₃ Ho/Ti₂O₃ Er/Ti₂O₃ Ti₃O Tb/Ti₃O Dy/Ti₃O Ho/Ti₃O Er/Ti₃O Ti₂O Tb/Ti₂O Dy/Ti₂O Ho/Ti₂O Er/Ti₂O Ti₃O₅ Tb/Ti₃O₅ Dy/Ti₃O₅ Ho/Ti₃O₅ Er/Ti₃O₅ Ti₄O₇ Tb/Ti₄O₇ Dy/Ti₄O₇ Ho/Ti₄O₇ Er/Ti₄O₇ ZrO₂ Tb/ZrO₂ Dy/ZrO₂ Ho/ZrO₂ Er/ZrO₂ HfO₂ Tb/HfO₂ Dy/HfO₂ Ho/HfO₂ Er/HfO₂ VO Tb/VO Dy/VO Ho/VO Er/VO V₂O₃ Tb/V₂O₃ Dy/V₂O₃ Ho/V₂O₃ Er/V₂O₃ VO₂ Tb/VO₂ Dy/VO₂ Ho/VO₂ Er/VO₂ V₂O₅ Tb/V₂O₅ Dy/V₂O₅ Ho/V₂O₅ Er/V₂O₅ V₃O₇ Tb/V₃O₇ Dy/V₃O₇ Ho/V₃O₇ Er/V₃O₇ V₄O₉ Tb/V₄O₉ Dy/V₄O₉ Ho/V₄O₉ Er/V₄O₉ V₆O₁₃ Tb/V₆O₁₃ Dy/V₆O₁₃ Ho/V₆O₁₃ Er/V₆O₁₃ NbO Tb/NbO Dy/NbO Ho/NbO Er/NbO NbO₂ Tb/NbO₂ Dy/NbO₂ Ho/NbO₂ Er/NbO₂ Nb₂O₅ Tb/Nb₂O₅ Dy/Nb₂O₅ Ho/Nb₂O₅ Er/Nb₂O₅ Nb₈O₁₉ Tb/Nb₈O₁₉ Dy/Nb₈O₁₉ Ho/Nb₈O₁₉ Er/Nb₈O₁₉ Nb₁₆O₃₈ Tb/Nb₁₆O₃₈ Dy/Nb₁₆O₃₈ Ho/Nb₁₆O₃₈ Er/Nb₁₆O₃₈ Nb₁₂O₂₉ Tb/Nb₁₂O₂₉ Dy/Nb₁₂O₂₉ Ho/Nb₁₂O₂₉ Er/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Tb/Nb₄₇O₁₁₆ Dy/Nb₄₇O₁₁₆ Ho/Nb₄₇O₁₁₆ Er/Nb₄₇O₁₁₆ Ta₂O₅ Tb/Ta₂O₅ Dy/Ta₂O₅ Ho/Ta₂O₅ Er/Ta₂O₅ CrO Tb/CrO Dy/CrO Ho/CrO Er/CrO Cr₂O₃ Tb/Cr₂O₃ Dy/Cr₂O₃ Ho/Cr₂O₃ Er/Cr₂O₃ CrO₂ Tb/CrO₂ Dy/CrO₂ Ho/CrO₂ Er/CrO₂ CrO₃ Tb/CrO₃ Dy/CrO₃ Ho/CrO₃ Er/CrO₃ Cr₈O₂₁ Tb/Cr₈O₂₁ Dy/Cr₈O₂₁ Ho/Cr₈O₂₁ Er/Cr₈O₂₁ MoO₂ Tb/MoO₂ Dy/MoO₂ Ho/MoO₂ Er/MoO₂ MoO₃ Tb/MoO₃ Dy/MoO₃ Ho/MoO₃ Er/MoO₃ W₂O₃ Tb/W₂O₃ Dy/W₂O₃ Ho/W₂O₃ Er/W₂O₃ WoO₂ Tb/WoO₂ Dy/WoO₂ Ho/WoO₂ Er/WoO₂ WoO₃ Tb/WoO₃ Dy/WoO₃ Ho/WoO₃ Er/WoO₃ MnO Tb/MnO Dy/MnO Ho/MnO Er/MnO Mn/Mg/O Tb/Mn/Mg/O Dy/Mn/Mg/O Ho/Mn/Mg/O Er/Mn/Mg/O Mn₃O₄ Tb/Mn₃O₄ Dy/Mn₃O₄ Ho/Mn₃O₄ Er/Mn₃O₄ Mn₂O₃ Tb/Mn₂O₃ Dy/Mn₂O₃ Ho/Mn₂O₃ Er/Mn₂O₃ MnO₂ Tb/MnO₂ Dy/MnO₂ Ho/MnO₂ Er/MnO₂ Mn₂O₇ Tb/Mn₂O₇ Dy/Mn₂O₇ Ho/Mn₂O₇ Er/Mn₂O₇ ReO₂ Tb/ReO₂ Dy/ReO₂ Ho/ReO₂ Er/ReO₂ ReO₃ Tb/ReO₃ Dy/ReO₃ Ho/ReO₃ Er/ReO₃ Re₂O₇ Tb/Re₂O₇ Dy/Re₂O₇ Ho/Re₂O₇ Er/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Tb/Mg₃Mn₃—B₂O₁₀ Dy/Mg₃Mn₃—B₂O₁₀ Ho/Mg₃Mn₃—B₂O₁₀ Er/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Tb/Mg₃(BO₃)₂ Dy/Mg₃(BO₃)₂ Ho/Mg₃(BO₃)₂ Er/Mg₃(BO₃)₂ NaWO₄ Tb/NaWO₄ Dy/NaWO₄ Ho/NaWO₄ Er/NaWO₄ Mg₆MnO₈ Tb/Mg₆MnO₈ Dy/Mg₆MnO₈ Ho/Mg₆MnO₈ Er/Mg₆MnO₈ Mn₂O₄ Tb/Mn₂O₄ Dy/Mn₂O₄ Ho/Mn₂O₄ Er/Mn₂O₄ (Li,Mg)₆MnO₈ Tb/(Li,Mg)₆MnO₈ Dy/(Li,Mg)₆MnO₈ Ho/(Li,Mg)₆MnO₈ Er/(Li,Mg)₆MnO₈ Na₄P₂O₇ Tb/Na₄P₂O₇ Dy/Na₄P₂O₇ Ho/Na₄P₂O₇ Er/Na₄P₂O₇ Mo₂O₈ Tb/Mo₂O₈ Dy/Mo₂O₈ Ho/Mo₂O₈ Er/Mo₂O₈ Mn₃O₄/WO₄ Tb/Mn₃O₄/WO₄ Dy/MnO₄/WO₄ Ho/Mn₃O₄/WO₄ Er/Mn₃O₄/WO₄ Na₂WO₄ Tb/Na₂WO₄ Dy/Na₂WO₄ Ho/Na₂WO₄ Er/Na₂WO₄ Zr₂Mo₂O₈ Tb/Zr₂Mo₂O₈ Dy/Zr₂Mo₂O₈ Ho/Zr₂Mo₂O₈ Er/Zr₂Mo₂O₈ NaMnO₄—/MgO Tb/NaMnO₄—/MgO Dy/NaMnO₄—/MgO Ho/NaMnO₄—/MgO Er/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Tb/Na₁₀Mn—W₅O₁₇ Dy/Na₁₀Mn—W₅O₁₇ Ho/Na₁₀Mn—W₅O₁₇ Er/Na₁₀Mn—W₅O₁₇ NW\Dop Tm Yb Lu In Li₂O Tm/Li₂O Yb/Li₂O Lu/Li₂O In/Li₂O Na₂O Tm/Na₂O Yb/Na₂O Lu/Na₂O In/Na₂O K₂O Tm/K₂O Yb/K₂O Lu/K₂O In/K₂O Rb₂O Tm/Rb₂O Yb/Rb₂O Lu/Rb₂O In/Rb₂O Cs₂O Tm/Cs₂O Yb/Cs₂O Lu/Cs₂O In/Cs₂O BeO Tm/BeO Yb/BeO Lu/BeO In/BeO MgO Tm/MgO Yb/MgO Lu/MgO In/MgO CaO Tm/CaO Yb/CaO Lu/CaO In/CaO SrO Tm/SrO Yb/SrO Lu/SrO In/SrO BaO Tm/BaO Yb/BaO Lu/BaO In/BaO Sc₂O₃ Tm/Sc₂O₃ Yb/Sc₂O₃ Lu/Sc₂O₃ In/Sc₂O₃ Y₂O₃ Tm/Y₂O₃ Yb/Y₂O₃ Lu/Y₂O₃ In/Y₂O₃ La₂O₃ Tm/La₂O₃ Yb/La₂O₃ Lu/La₂O₃ In/La₂O₃ CeO₂ Tm/CeO₂ Yb/CeO₂ Lu/CeO₂ In/CeO₂ Ce₂O₃ Tm/Ce₂O₃ Yb/Ce₂O₃ Lu/Ce₂O₃ In/Ce₂O₃ Pr₂O₃ Tm/Pr₂O₃ Yb/Pr₂O₃ Lu/Pr₂O₃ In/Pr₂O₃ Nd₂O₃ Tm/Nd₂O₃ Yb/Nd₂O₃ Lu/Nd₂O₃ In/Nd₂O₃ Sm₂O₃ Tm/Sm₂O₃ Yb/Sm₂O₃ Lu/Sm₂O₃ In/Sm₂O₃ Eu₂O₃ Tm/Eu₂O₃ Yb/Eu₂O₃ Lu/Eu₂O₃ In/Eu₂O₃ Gd₂O₃ Tm/Gd₂O₃ Yb/Gd₂O₃ Lu/Gd₂O₃ In/Gd₂O₃ Tb₂O₃ Tm/Tb₂O₃ Yb/Tb₂O₃ Lu/Tb₂O₃ In/Tb₂O₃ TbO₂ Tm/TbO₂ Yb/TbO₂ Lu/TbO₂ In/TbO₂ Tb₆O₁₁ Tm/Tb₆O₁₁ Yb/Tb₆O₁₁ Lu/Tb₆O₁₁ In/Tb₆O₁₁ Dy₂O₃ Tm/Dy₂O₃ Yb/Dy₂O₃ Lu/Dy₂O₃ In/Dy₂O₃ Ho₂O₃ Tm/Ho₂O₃ Yb/Ho₂O₃ Lu/Ho₂O₃ In/Ho₂O₃ Er₂O₃ Tm/Er₂O₃ Yb/Er₂O₃ Lu/Er₂O₃ In/Er₂O₃ Tm₂O₃ Tm/Tm₂O₃ Yb/Tm₂O₃ Lu/Tm₂O₃ In/Tm₂O₃ Yb₂O₃ Tm/Yb₂O₃ Yb/Yb₂O₃ Lu/Yb₂O₃ In/Yb₂O₃ Lu₂O₃ Tm/Lu₂O₃ Yb/Lu₂O₃ Lu/Lu₂O₃ In/Lu₂O₃ Ac₂O₃ Tm/Ac₂O₃ Yb/Ac₂O₃ Lu/Ac₂O₃ In/Ac₂O₃ Th₂O₃ Tm/Th₂O₃ Yb/Th₂O₃ Lu/Th₂O₃ In/Th₂O₃ ThO₂ Tm/ThO₂ Yb/ThO₂ Lu/ThO₂ In/ThO₂ Pa₂O₃ Tm/Pa₂O₃ Yb/Pa₂O₃ Lu/Pa₂O₃ In/Pa₂O₃ PaO₂ Tm/PaO₂ Yb/PaO₂ Lu/PaO₂ In/PaO₂ TiO₂ Tm/TiO₂ Yb/TiO₂ Lu/TiO₂ In/TiO₂ TiO Tm/TiO Yb/TiO Lu/TiO In/TiO Ti₂O₃ Tm/Ti₂O₃ Yb/Ti₂O₃ Lu/Ti₂O₃ In/Ti₂O₃ Ti₃O Tm/Ti₃O Yb/Ti₃O Lu/Ti₃O In/Ti₃O Ti₂O Tm/Ti₂O Yb/Ti₂O Lu/Ti₂O In/Ti₂O Ti₃O₅ Tm/Ti₃O₅ Yb/Ti₃O₅ Lu/Ti₃O₅ In/Ti₃O₅ Ti₄O₇ Tm/Ti₄O₇ Yb/Ti₄O₇ Lu/Ti₄O₇ In/Ti₄O₇ ZrO₂ Tm/ZrO₂ Yb/ZrO₂ Lu/ZrO₂ In/ZrO₂ HfO₂ Tm/HfO₂ Yb/HfO₂ Lu/HfO₂ In/HfO₂ VO Tm/VO Yb/VO Lu/VO In/VO V₂O₃ Tm/V₂O₃ Yb/V₂O₃ Lu/V₂O₃ In/V₂O₃ VO₂ Tm/VO₂ Yb/VO₂ Lu/VO₂ In/VO₂ V₂O₅ Tm/V₂O₅ Yb/V₂O₅ Lu/V₂O₅ In/V₂O₅ V₃O₇ Tm/V₃O₇ Yb/V₃O₇ Lu/V₃O₇ In/V₃O₇ V₄O₉ Tm/V₄O₉ Yb/V₄O₉ Lu/V₄O₉ In/V₄O₉ V₆O₁₃ Tm/V₆O₁₃ Yb/V₆O₁₃ Lu/V₆O₁₃ In/V₆O₁₃ NbO Tm/NbO Yb/NbO Lu/NbO In/NbO NbO₂ Tm/NbO₂ Yb/NbO₂ Lu/NbO₂ In/NbO₂ Nb₂O₅ Tm/Nb₂O₅ Yb/Nb₂O₅ Lu/Nb₂O₅ In/Nb₂O₅ Nb₈O₁₉ Tm/Nb₈O₁₉ Yb/Nb₈O₁₉ Lu/Nb₈O₁₉ In/Nb₈O₁₉ Nb₁₆O₃₈ Tm/Nb₁₆O₃₈ Yb/Nb₁₆O₃₈ Lu/Nb₁₆O₃₈ In/Nb₁₆O₃₈ Nb₁₂O₂₉ Tm/Nb₁₂O₂₉ Yb/Nb₁₂O₂₉ Lu/Nb₁₂O₂₉ In/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Tm/Nb₄₇O₁₁₆ Yb/Nb₄₇O₁₁₆ Lu/Nb₄₇O₁₁₆ In/Nb₄₇O₁₁₆ Ta₂O₅ Tm/Ta₂O₅ Yb/Ta₂O₅ Lu/Ta₂O₅ In/Ta₂O₅ CrO Tm/CrO Yb/CrO Lu/CrO In/CrO Cr₂O₃ Tm/Cr₂O₃ Yb/Cr₂O₃ Lu/Cr₂O₃ In/Cr₂O₃ CrO₂ Tm/CrO₂ Yb/CrO₂ Lu/CrO₂ In/CrO₂ CrO₃ Tm/CrO₃ Yb/CrO₃ Lu/CrO₃ In/CrO₃ Cr₈O₂₁ Tm/Cr₈O₂₁ Yb/Cr₈O₂₁ Lu/Cr₈O₂₁ In/Cr₈O₂₁ MoO₂ Tm/MoO₂ Yb/MoO₂ Lu/MoO₂ In/MoO₂ MoO₃ Tm/MoO₃ Yb/MoO₃ Lu/MoO₃ In/MoO₃ W₂O₃ Tm/W₂O₃ Yb/W₂O₃ Lu/W₂O₃ In/W₂O₃ WoO₂ Tm/WoO₂ Yb/WoO₂ Lu/WoO₂ In/WoO₂ WoO₃ Tm/WoO₃ Yb/WoO₃ Lu/WoO₃ In/WoO₃ MnO Tm/MnO Yb/MnO Lu/MnO In/MnO Mn/Mg/O Tm/Mn/Mg/O Yb/Mn/Mg/O Lu/Mn/Mg/O In/Mn/Mg/O Mn₃O₄ Tm/Mn₃O₄ Yb/Mn₃O₄ Lu/Mn₃O₄ In/Mn₃O₄ Mn₂O₃ Tm/Mn₂O₃ Yb/Mn₂O₃ Lu/Mn₂O₃ In/Mn₂O₃ MnO₂ Tm/MnO₂ Yb/MnO₂ Lu/MnO₂ In/MnO₂ Mn₂O₇ Tm/Mn₂O₇ Yb/Mn₂O₇ Lu/Mn₂O₇ In/Mn₂O₇ ReO₂ Tm/ReO₂ Yb/ReO₂ Lu/ReO₂ In/ReO₂ ReO₃ Tm/ReO₃ Yb/ReO₃ Lu/ReO₃ In/ReO₃ Re₂O₇ Tm/Re₂O₇ Yb/Re₂O₇ Lu/Re₂O₇ In/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Tm/Mg₃Mn₃—B₂O₁₀ Yb/Mg₃Mn₃—B₂O₁₀ Lu/Mg₃Mn₃—B₂O₁₀ In/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Tm/Mg₃(BO₃)₂ Yb/Mg₃(BO₃)₂ Lu/Mg₃(BO₃)₂ In/Mg₃(BO₃)₂ NaWO₄ Tm/NaWO₄ Yb/NaWO₄ Lu/NaWO₄ In/NaWO₄ Mg₆MnO₈ Tm/Mg₆MnO₈ Yb/Mg₆MnO₈ Lu/Mg₆MnO₈ In/Mg₆MnO₈ Mn₂O₄ Tm/Mn₂O₄ Yb/Mn₂O₄ Lu/Mn₂O₄ In/Mn₂O₄ (Li,Mg)₆MnO₈ Tm/(Li,Mg)₆MnO₈ Yb/(Li,Mg)₆MnO₈ Lu/(Li,Mg)₆MnO₈ In/(Li,Mg)₆MnO₈ Na₄P₂O₇ Tm/Na₄P₂O₇ Yb/Na₄P₂O₇ Lu/Na₄P₂O₇ In/Na₄P₂O₇ Mo₂O₈ Tm/Mo₂O₈ Yb/Mo₂O₈ Lu/Mo₂O₈ In/Mo₂O₈ Mn₃O₄/WO₄ Tm/Mn₃O₄/WO₄ Yb/Mn₃O₄/WO₄ Lu/Mn₃O₄/WO₄ In/Mn₃O₄/WO₄ Na₂WO₄ Tm/Na₂WO₄ Yb/Na₂WO₄ Lu/Na₂WO₄ In/Na₂WO₄ Zr₂Mo₂O₈ Tm/Zr₂Mo₂O₈ Yb/Zr₂Mo₂O₈ Lu/Zr₂Mo₂O₈ In/Zr₂Mo₂O₈ NaMnO₄—/MgO Tm/NaMnO₄—/MgO Yb/NaMnO₄—/MgO Lu/NaMnO₄—/MgO In/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Tm/Na₁₀Mn—W₅O₁₇ Yb/Na₁₀Mn—W₅O₁₇ Lu/Na₁₀Mn—W₅O₁₇ In/Na₁₀Mn—W₅O₁₇

TABLE 5 NANOWIRES (NW) DOPED WITH SPECIFIC DOPANTS (DOP) NW\Dop Y Sc Al Cu Ga Li₂O Y/Li₂O Sc/Li₂O Al/Li₂O Cu/Li₂O Ga/Li₂O Na₂O Y/Na₂O Sc/Na₂O Al/Na₂O Cu/Na₂O Ga/Na₂O K₂O Y/K₂O Sc/K₂O Al/K₂O Cu/K₂O Ga/K₂O Rb₂O Y/Rb₂O Sc/Rb₂O Al/Rb₂O Cu/Rb₂O Ga/Rb₂O Cs₂O Y/Cs₂O Sc/Cs₂O Al/Cs₂O Cu/Cs₂O Ga/Cs₂O BeO Y/BeO Sc/BeO Al/BeO Cu/BeO Ga/BeO MgO Y/MgO Sc/MgO Al/MgO Cu/MgO Ga/MgO CaO Y/CaO Sc/CaO Al/CaO Cu/CaO Ga/CaO SrO Y/SrO Sc/SrO Al/SrO Cu/SrO Ga/SrO BaO Y/BaO Sc/BaO Al/BaO Cu/BaO Ga/BaO Sc₂O₃ Y/Sc₂O₃ Sc/Sc₂O₃ Al/Sc₂O₃ Cu/Sc₂O₃ Ga/Sc₂O₃ Y₂O₃ Y/Y₂O₃ Sc/Y₂O₃ Al/Y₂O₃ Cu/Y₂O₃ Ga/Y₂O₃ La₂O₃ Y/La₂O₃ Sc/La₂O₃ Al/La₂O₃ Cu/La₂O₃ Ga/La₂O₃ CeO₂ Y/CeO₂ Sc/CeO₂ Al/CeO₂ Cu/CeO₂ Ga/CeO₂ Ce₂O₃ Y/Ce₂O₃ Sc/Ce₂O₃ Al/Ce₂O₃ Cu/Ce₂O₃ Ga/Ce₂O₃ Pr₂O₃ Y/Pr₂O₃ Sc/Pr₂O₃ Al/Pr₂O₃ Cu/Pr₂O₃ Ga/Pr₂O₃ Nd₂O₃ Y/Nd₂O₃ Sc/Nd₂O₃ Al/Nd₂O₃ Cu/Nd₂O₃ Ga/Nd₂O₃ Sm₂O₃ Y/Sm₂O₃ Sc/Sm₂O₃ Al/Sm₂O₃ Cu/Sm₂O₃ Ga/Sm₂O₃ Eu₂O₃ Y/Eu₂O₃ Sc/Eu₂O₃ Al/Eu₂O₃ Cu/Eu₂O₃ Ga/Eu₂O₃ Gd₂O₃ Y/Gd₂O₃ Sc/Gd₂O₃ Al/Gd₂O₃ Cu/Gd₂O₃ Ga/Gd₂O₃ Tb₂O₃ Y/Tb₂O₃ Sc/Tb₂O₃ Al/Tb₂O₃ Cu/Tb₂O₃ Ga/Tb₂O₃ TbO₂ Y/TbO₂ Sc/TbO₂ Al/TbO₂ Cu/TbO₂ Ga/TbO₂ Tb₆O₁₁ Y/Tb₆O₁₁ Sc/Tb₆O₁₁ Al/Tb₆O₁₁ Cu/Tb₆O₁₁ Ga/Tb₆O₁₁ Dy₂O₃ Y/Dy₂O₃ Sc/Dy₂O₃ Al/Dy₂O₃ Cu/DyO₃ Ga/Dy₂O₃ Ho₂O₃ Y/Ho₂O₃ Sc/Ho₂O₃ Al/Ho₂O₃ Cu/Ho₂O₃ Ga/Ho₂O₃ Er₂O₃ Y/Er₂O₃ Sc/Er₂O₃ Al/Er₂O₃ Cu/Er₂O₃ Ga/Er₂O₃ Tm₂O₃ Y/Tm₂O₃ Sc/Tm₂O₃ Al/Tm₂O₃ Cu/Tm₂O₃ Ga/Tm₂O₃ Yb₂O₃ Y/Yb₂O₃ Sc/Yb₂O₃ Al/Yb₂O₃ Cu/Yb₂O₃ Ga/Yb₂O₃ Lu₂O₃ Y/Lu₂O₃ Sc/Lu₂O₃ Al/Lu₂O₃ Cu/Lu₂O₃ Ga/Lu₂O₃ Ac₂O₃ Y/Ac₂O₃ Sc/Ac₂O₃ Al/Ac₂O₃ Cu/Ac₂O₃ Ga/Ac₂O₃ Th₂O₃ Y/Th₂O₃ Sc/Th₂O₃ Al/Th₂O₃ Cu/Th₂O₃ Ga/Th₂O₃ ThO₂ Y/ThO₂ Sc/ThO₂ Al/ThO₂ Cu/ThO₂ Ga/ThO₂ Pa₂O₃ Y/Pa₂O₃ Sc/Pa₂O₃ Al/Pa₂O₃ Cu/Pa₂O₃ Ga/Pa₂O₃ PaO₂ Y/PaO₂ Sc/PaO₂ Al/PaO₂ Cu/PaO₂ Ga/PaO₂ TiO₂ Y/TiO₂ Sc/TiO₂ Al/TiO₂ Cu/TiO₂ Ga/TiO₂ TiO Y/TiO Sc/TiO Al/TiO Cu/TiO Ga/TiO Ti₂O₃ Y/Ti₂O₃ Sc/Ti₂O₃ Al/Ti₂O₃ Cu/Ti₂O₃ Ga/Ti₂O₃ Ti₃O Y/Ti₃O Sc/Ti₃O Al/Ti₃O Cu/Ti₃O Ga/Ti₃O Ti₂O Y/Ti₂O Sc/Ti₂O Al/Ti₂O Cu/Ti₂O Ga/Ti₂O Ti₃O₅ Y/Ti₃O₅ Sc/Ti₃O₅ Al/Ti₃O₅ Cu/Ti₃O₅ Ga/Ti₃O₅ Ti₄O₇ Y/Ti₄O₇ Sc/Ti₄O₇ Al/Ti₄O₇ Cu/Ti₄O₇ Ga/Ti₄O₇ ZrO₂ Y/ZrO₂ Sc/ZrO₂ Al/ZrO₂ Cu/ZrO₂ Ga/ZrO₂ HfO₂ Y/HfO₂ Sc/HfO₂ Al/HfO₂ Cu/HfO₂ Ga/HfO₂ VO Y/VO Sc/VO Al/VO Cu/VO Ga/VO V₂O₃ Y/V₂O₃ Sc/V₂O₃ Al/V₂O₃ Cu/V₂O₃ Ga/V₂O₃ VO₂ Y/VO₂ Sc/VO₂ Al/VO₂ Cu/VO₂ Ga/VO₂ V₂O₅ Y/V₂O₅ Sc/V₂O₅ Al/V₂O₅ Cu/V₂O₅ Ga/V₂O₅ V₃O₇ Y/V₃O₇ Sc/V₃O₇ Al/V₃O₇ Cu/V₃O₇ Ga/V₃O₇ V₄O₉ Y/V₄O₉ Sc/V₄O₉ Al/V₄O₉ Cu/V₄O₉ Ga/V₄O₉ V₆O₁₃ Y/V₆O₁₃ Sc/V₆O₁₃ Al/V₆O₁₃ Cu/V₆O₁₃ Ga/V₆O₁₃ NbO Y/NbO Sc/NbO Al/NbO Cu/NbO Ga/NbO NbO₂ Y/NbO₂ Sc/NbO₂ Al/NbO₂ Cu/NbO₂ Ga/NbO₂ Nb₂O₅ Y/Nb₂O₅ Sc/Nb₂O₅ Al/Nb₂O₅ Cu/Nb₂O₅ Ga/Nb₂O₅ Nb₈O₁₉ Y/Nb₈O₁₉ Sc/Nb₈O₁₉ Al/Nb₈O₁₉ Cu/Nb₈O₁₉ Ga/Nb₈O₁₉ Nb₁₆O₃₈ Y/Nb₁₆O₃₈ Sc/Nb₁₆O₃₈ Al/Nb₁₆O₃₈ Cu/Nb₁₆O₃₈ Ga/Nb₁₆O₃₈ Nb₁₂O₂₉ Y/Nb₁₂O₂₉ Sc/Nb₁₂O₂₉ Al/Nb₁₂O₂₉ Cu/Nb₁₂O₂₉ Ga/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Y/Nb₄₇O₁₁₆ Sc/Nb₄₇O₁₁₆ Al/Nb₄₇O₁₁₆ Cu/Nb₄₇O₁₁₆ Ga/Nb₄₇O₁₁₆ Ta₂O₅ Y/Ta₂O₅ Sc/Ta₂O₅ Al/Ta₂O₅ Cu/Ta₂O₅ Ga/Ta₂O₅ CrO Y/CrO Sc/CrO Al/CrO Cu/CrO Ga/CrO Cr₂O₃ Y/Cr₂O₃ Sc/Cr₂O₃ Al/Cr₂O₃ Cu/Cr₂O₃ Ga/Cr₂O₃ CrO₂ Y/CrO₂ Sc/CrO₂ Al/CrO₂ Cu/CrO₂ Ga/CrO₂ CrO₃ Y/CrO₃ Sc/CrO₃ Al/CrO₃ Cu/CrO₃ Ga/CrO₃ Cr₈O₂₁ Y/Cr₈O₂₁ Sc/Cr₈O₂₁ Al/Cr₈O₂₁ Cu/Cr₈O₂₁ Ga/Cr₈O₂₁ MoO₂ Y/MoO₂ Sc/MoO₂ Al/MoO₂ Cu/MoO₂ Ga/MoO₂ MoO₃ Y/MoO₃ Sc/MoO₃ Al/MoO₃ Cu/MoO₃ Ga/MoO₃ W₂O₃ Y/W₂O₃ Sc/W₂O₃ Al/W₂O₃ Cu/W₂O₃ Ga/W₂O₃ WoO₂ Y/WoO₂ Sc/WoO₂ Al/WoO₂ Cu/WoO₂ Ga/WoO₂ WoO₃ Y/WoO₃ Sc/WoO₃ Al/WoO₃ Cu/WoO₃ Ga/WoO₃ MnO Y/MnO Sc/MnO Al/MnO Cu/MnO Ga/MnO Mn/Mg/O Y/Mn/Mg/O Sc/Mn/Mg/O Al/Mn/Mg/O Cu/Mn/Mg/O Ga/Mn/Mg/O Mn₃O₄ Y/Mn₃O₄ Sc/Mn₃O₄ Al/Mn₃O₄ Cu/Mn₃O₄ Ga/Mn₃O₄ Mn₂O₃ Y/Mn₂O₃ Sc/Mn₂O₃ Al/Mn₂O₃ Cu/Mn₂O₃ Ga/Mn₂O₃ MnO₂ Y/MnO₂ Sc/MnO₂ Al/MnO₂ Cu/MnO₂ Ga/MnO₂ Mn₂O₇ Y/Mn₂O₇ Sc/Mn₂O₇ Al/Mn₂O₇ Cu/Mn₂O₇ Ga/Mn₂O₇ ReO₂ Y/ReO₂ Sc/ReO₂ Al/ReO₂ Cu/ReO₂ Ga/ReO₂ ReO₃ Y/ReO₃ Sc/ReO₃ Al/ReO₃ Cu/ReO₃ Ga/ReO₃ Re₂O₇ Y/Re₂O₇ Sc/Re₂O₇ Al/Re₂O₇ Cu/Re₂O₇ Ga/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Y/Mg₃Mn₃—B₂O₁₀ Sc/Mg₃Mn₃—B₂O₁₀ Al/Mg₃Mn₃—B₂O₁₀ Cu/Mg₃Mn₃—B₂O₁₀ Ga/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Y/Mg₃(BO₃)₂ Sc/Mg₃(BO₃)₂ Al/Mg₃(BO₃)₂ Cu/Mg₃(BO₃)₂ Ga/Mg₃(BO₃)₂ NaWO₄ Y/NaWO₄ Sc/NaWO₄ Al/NaWO₄ Cu/NaWO₄ Ga/NaWO₄ Mg₆MnO₈ Y/Mg₆MnO₈ Sc/Mg₆MnO₈ Al/Mg₆MnO₈ Cu/Mg₆MnO₈ Ga/Mg₆MnO₈ Mn₂O₄ Y/Mn₂O₄ Sc/Mn₂O₄ Al/Mn₂O₄ Cu/Mn₂O₄ Ga/Mn₂O₄ (Li,Mg)₆MnO₈ Y/(Li,Mg)₆MnO₈ Sc/(Li,Mg)₆MnO₈ Al/(Li,Mg)₆MnO₈ Cu/(Li,Mg)₆MnO₈ Ga/(Li,Mg)₆MnO₈ Na₄P₂O₇ Y/Na₄P₂O₇ Sc/Na₄P₂O₇ Al/Na₄P₂O₇ Cu/Na₄P₂O₇ Ga/Na₄P₂O₇ Mo₂O₈ Y/Mo₂O₈ Sc/Mo₂O₈ Al/Mo₂O₈ Cu/Mo₂O₈ Ga/Mo₂O₈ Mn₃O₄/WO₄ Y/Mn₃O₄/WO₄ Sc/Mn₃O₄/WO₄ Al/Mn₃O₄/WO₄ Cu/Mn₃O₄/WO₄ Ga/Mn₃O₄/WO₄ Na₂WO₄ Y/Na₂WO₄ Sc/Na₂WO₄ Al/Na₂WO₄ Cu/Na₂WO₄ Ga/Na₂WO₄ Zr₂Mo₂O₈ Y/Zr₂Mo₂O₈ Sc/Zr₂Mo₂O₈ Al/Zr₂Mo₂O₈ Cu/Zr₂Mo₂O₈ Ga/Zr₂Mo₂O₈ NaMnO₄—/MgO Y/NaMnO₄—/MgO Sc/NaMnO₄—/MgO Al/NaMnO₄—/MgO Cu/NaMnO₄—/MgO Ga/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Y/Na₁₀Mn—W₅O₁₇ Sc/Na₁₀Mn—W₅O₁₇ Al/Na₁₀Mn—W₅O₁₇ Cu/Na₁₀Mn—W₅O₁₇ Ga/Na₁₀Mn—W₅O₁₇ NW\Dop Hf Fe Cr Li₂O Hf/Li₂O Fe/Li₂O Cr/Li₂O Na₂O Hf/Na₂O Fe/Na₂O Cr/Na₂O K₂O Hf/K₂O Fe/K₂O Cr/K₂O Rb₂O Hf/Rb₂O Fe/Rb₂O Cr/Rb₂O Cs₂O Hf/Cs₂O Fe/Cs₂O Cr/Cs₂O BeO Hf/BeO Fe/BeO Cr/BeO MgO Hf/MgO Fe/MgO Cr/MgO CaO Hf/CaO Fe/CaO Cr/CaO SrO Hf/SrO Fe/SrO Cr/SrO BaO Hf/BaO Fe/BaO Cr/BaO Sc₂O₃ Hf/Sc₂O₃ Fe/Sc₂O₃ Cr/Sc₂O₃ Y₂O₃ Hf/Y₂O₃ Fe/Y₂O₃ Cr/Y₂O₃ La₂O₃ Hf/La₂O₃ Fe/La₂O₃ Cr/La₂O₃ CeO₂ Hf/CeO₂ Fe/CeO₂ Cr/CeO₂ Ce₂O₃ Hf/Ce₂O₃ Fe/Ce₂O₃ Cr/Ce₂O₃ Pr₂O₃ Hf/Pr₂O₃ Fe/Pr₂O₃ Cr/Pr₂O₃ Nd₂O₃ Hf/Nd₂O₃ Fe/Nd₂O₃ Cr/Nd₂O₃ Sm₂O₃ Hf/Sm₂O₃ Fe/Sm₂O₃ Cr/Sm₂O₃ Eu₂O₃ Hf/Eu₂O₃ Fe/Eu₂O₃ Cr/Eu₂O₃ Gd₂O₃ Hf/Gd₂O₃ Fe/Gd₂O₃ Cr/Gd₂O₃ Tb₂O₃ Hf/Tb₂O₃ Fe/Tb₂O₃ Cr/Tb₂O₃ TbO₂ Hf/TbO₂ Fe/TbO₂ Cr/TbO₂ Tb₆O₁₁ Hf/Tb₆O₁₁ Fe/Tb₆O₁₁ Cr/Tb₆O₁₁ Dy₂O₃ Hf/DyO₃ Fe/Dy₂O₃ Cr/Dy₂O₃ Ho₂O₃ Hf/Ho₂O₃ Fe/Ho₂O₃ Cr/Ho₂O₃ Er₂O₃ Hf/Er₂O₃ Fe/Er₂O₃ Cr/Er₂O₃ Tm₂O₃ Hf/Tm₂O₃ Fe/Tm₂O₃ Cr/Tm₂O₃ Yb₂O₃ Hf/Yb₂O₃ Fe/Yb₂O₃ Cr/Yb₂O₃ Lu₂O₃ Hf/Lu₂O₃ Fe/Lu₂O₃ Cr/Lu₂O₃ Ac₂O₃ Hf/Ac₂O₃ Fe/Ac₂O₃ Cr/Ac₂O₃ Th₂O₃ Hf/Th₂O₃ Fe/Th₂O₃ Cr/Th₂O₃ ThO₂ Hf/ThO₂ Fe/ThO₂ Cr/ThO₂ Pa₂O₃ Hf/Pa₂O₃ Fe/Pa₂O₃ Cr/Pa₂O₃ PaO₂ Hf/PaO₂ Fe/PaO₂ Cr/PaO₂ TiO₂ Hf/TiO₂ Fe/TiO₂ Cr/TiO₂ TiO Hf/TiO Fe/TiO Cr/TiO Ti₂O₃ Hf/Ti₂O₃ Fe/Ti₂O₃ Cr/Ti₂O₃ Ti₃O Hf/Ti₃O Fe/Ti₃O Cr/Ti₃O Ti₂O Hf/Ti₂O Fe/Ti₂O Cr/Ti₂O Ti₃O₅ Hf/Ti₃O₅ Fe/Ti₃O₅ Cr/Ti₃O₅ Ti₄O₇ Hf/Ti₄O₇ Fe/Ti₄O₇ Cr/Ti₄O₇ ZrO₂ Hf/ZrO₂ Fe/ZrO₂ Cr/ZrO₂ HfO₂ Hf/HfO₂ Fe/HfO₂ Cr/HfO₂ VO Hf/VO Fe/VO Cr/VO V₂O₃ Hf/V₂O₃ Fe/V₂O₃ Cr/V₂O₃ VO₂ Hf/VO₂ Fe/VO₂ Cr/VO₂ V₂O₅ Hf/V₂O₅ Fe/V₂O₅ Cr/V₂O₅ V₃O₇ Hf/V₃O₇ Fe/V₃O₇ Cr/V₃O₇ V₄O₉ Hf/V₄O₉ Fe/V₄O₉ Cr/V₄O₉ V₆O₁₃ Hf/V₆O₁₃ Fe/V₆O₁₃ Cr/V₆O₁₃ NbO Hf/NbO Fe/NbO Cr/NbO NbO₂ Hf/NbO₂ Fe/NbO₂ Cr/NbO₂ Nb₂O₅ Hf/Nb₂O₅ Fe/Nb₂O₅ Cr/Nb₂O₅ Nb₈O₁₉ Hf/Nb₈O₁₉ Fe/Nb₈O₁₉ Cr/Nb₈O₁₉ Nb₁₆O₃₈ Hf/Nb₁₆O₃₈ Fe/Nb₁₆O₃₈ Cr/Nb₁₆O₃₈ Nb₁₂O₂₉ Hf/Nb₁₂O₂₉ Fe/Nb₁₂O₂₉ Cr/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Hf/Nb₄₇O₁₁₆ Fe/Nb₄₇O₁₁₆ Cr/Nb₄₇O₁₁₆ Ta₂O₅ Hf/Ta₂O₅ Fe/Ta₂O₅ Cr/Ta₂O₅ CrO Hf/CrO Fe/CrO Cr/CrO Cr₂O₃ Hf/Cr₂O₃ Fe/Cr₂O₃ Cr/Cr₂O₃ CrO₂ Hf/CrO₂ Fe/CrO₂ Cr/CrO₂ CrO₃ Hf/CrO₃ Fe/CrO₃ Cr/CrO₃ Cr₈O₂₁ Hf/Cr₈O₂₁ Fe/Cr₈O₂₁ Cr/Cr₈O₂₁ MoO₂ Hf/MoO₂ Fe/MoO₂ Cr/MoO₂ MoO₃ Hf/MoO₃ Fe/MoO₃ Cr/MoO₃ W₂O₃ Hf/W₂O₃ Fe/W₂O₃ Cr/W₂O₃ WoO₂ Hf/WoO₂ Fe/WoO₂ Cr/WoO₂ WoO₃ Hf/WoO₃ Fe/WoO₃ Cr/WoO₃ MnO Hf/MnO Fe/MnO Cr/MnO Mn/Mg/O Hf/Mn/Mg/O Fe/Mn/Mg/O Cr/Mn/Mg/O Mn₃O₄ Hf/Mn₃O₄ Fe/Mn₃O₄ Cr/Mn₃O₄ Mn₂O₃ Hf/Mn₂O₃ Fe/Mn₂O₃ Cr/Mn₂O₃ MnO₂ Hf/MnO₂ Fe/MnO₂ Cr/MnO₂ Mn₂O₇ Hf/Mn₂O₇ Fe/Mn₂O₇ Cr/Mn₂O₇ ReO₂ Hf/ReO₂ Fe/ReO₂ Cr/ReO₂ ReO₃ Hf/ReO₃ Fe/ReO₃ Cr/ReO₃ Re₂O₇ Hf/Re₂O₇ Fe/Re₂O₇ Cr/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Hf/Mg₃Mn₃—B₂O₁₀ Fe/Mg₃Mn₃—B₂O₁₀ Cr/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Hf/Mg₃(BO₃)₂ Fe/Mg₃(BO₃)₂ Cr/Mg₃(BO₃)₂ NaWO₄ Hf/NaWO₄ Fe/NaWO₄ Cr/NaWO₄ Mg₆MnO₈ Hf/Mg₆MnO₈ Fe/Mg₆MnO₈ Cr/Mg₆MnO₈ Mn₂O₄ Hf/Mn₂O₄ Fe/Mn₂O₄ Cr/Mn₂O₄ (Li,Mg)₆MnO₈ Hf/(Li,Mg)₆MnO₈ Fe/(Li,Mg)₆MnO₈ Cr/(Li,Mg)₆MnO₈ Na₄P₂O₇ Hf/Na₄P₂O₇ Fe/Na₄P₂O₇ Cr/Na₄P₂O₇ Mo₂O₈ Hf/Mo₂O₈ Fe/Mo₂O₈ Cr/Mo₂O₈ Mn₃O₄/WO₄ Hf/Mn₃O₄/WO₄ Fe/Mn₃O₄/WO₄ Cr/Mn₃O₄/WO₄ Na₂WO₄ Hf/Na₂WO₄ Fe/Na₂WO₄ Cr/Na₂WO₄ Zr₂Mo₂O₈ Hf/Zr₂Mo₂O₈ Fe/Zr₂Mo₂O₈ Cr/Zr₂Mo₂O₈ NaMnO₄—/MgO Hf/NaMnO₄—/MgO Fe/NaMnO₄—/MgO Cr/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Hf/Na₁₀Mn—W₅O₁₇ Fe/Na₁₀Mn—W₅O₁₇ Cr/Na₁₀Mn—W₅O₁₇

TABLE 6 NANOWIRES (NW) DOPED WITH SPECIFIC DOPANTS (DOP) NW\Dop Ru Sr Zr Ta Rh Li₂O Ru/Li₂O Sr/Li₂O Zr/Li₂O Ta/Li₂O Rh/Li₂O Na₂O Ru/Na₂O Sr/Na₂O Zr/Na₂O Ta/Na₂O Rh/Na₂O K₂O Ru/K₂O Sr/K₂O Zr/K₂O Ta/K₂O Rh/K₂O Rb₂O Ru/Rb₂O Sr/Rb₂O Zr/Rb₂O Ta/Rb₂O Rh/Rb₂O Cs₂O Ru/Cs₂O Sr/Cs₂O Zr/Cs₂O Ta/Cs₂O Rh/Cs₂O BeO Ru/BeO Sr/BeO Zr/BeO Ta/BeO Rh/BeO MgO Ru/MgO Sr/MgO Zr/MgO Ta/MgO Rh/MgO CaO Ru/CaO Sr/CaO Zr/CaO Ta/CaO Rh/CaO SrO Ru/SrO Sr/SrO Zr/SrO Ta/SrO Rh/SrO BaO Ru/BaO Sr/BaO Zr/BaO Ta/BaO Rh/BaO Sc₂O₃ Ru/Sc₂O₃ Sr/Sc₂O₃ Zr/Sc₂O₃ Ta/Sc₂O₃ Rh/Sc₂O₃ Y₂O₃ Ru/Y₂O₃ Sr/Y₂O₃ Zr/Y₂O₃ Ta/Y₂O₃ Rh/Y₂O₃ La₂O₃ Ru/La₂O₃ Sr/La₂O₃ Zr/La₂O₃ Ta/La₂O₃ Rh/La₂O₃ CeO₂ Ru/CeO₂ Sr/CeO₂ Zr/CeO₂ Ta/CeO₂ Rh/CeO₂ Ce₂O₃ Ru/Ce₂O₃ Sr/Ce₂O₃ Zr/Ce₂O₃ Ta/Ce₂O₃ Rh/Ce₂O₃ Pr₂O₃ Ru/Pr₂O₃ Sr/Pr₂O₃ Zr/Pr₂O₃ Ta/Pr₂O₃ Rh/Pr₂O₃ Nd₂O₃ Ru/Nd₂O₃ Sr/Nd₂O₃ Zr/Nd₂O₃ Ta/Nd₂O₃ Rh/Nd₂O₃ Sm₂O₃ Ru/Sm₂O₃ Sr/Sm₂O₃ Zr/Sm₂O₃ Ta/Sm₂O₃ Rh/Sm₂O₃ Eu₂O₃ Ru/Eu₂O₃ Sr/Eu₂O₃ Zr/Eu₂O₃ Ta/Eu₂O₃ Rh/Eu₂O₃ Gd₂O₃ Ru/Gd₂O₃ Sr/Gd₂O₃ Zr/Gd₂O₃ Ta/Gd₂O₃ Rh/Gd₂O₃ Tb₂O₃ Ru/Tb₂O₃ Sr/Tb₂O₃ Zr/Tb₂O₃ Ta/Tb₂O₃ Rh/Tb₂O₃ TbO₂ Ru/TbO₂ Sr/TbO₂ Zr/TbO₂ Ta/TbO₂ Rh/TbO₂ Tb₆O₁₁ Ru/Tb₆O₁₁ Sr/Tb₆O₁₁ Zr/Tb₆O₁₁ Ta/Tb₆O₁₁ Rh/Tb₆O₁₁ Dy₂O₃ Ru/Dy₂O₃ Sr/Dy₂O₃ Zr/Dy₂O₃ Ta/Dy₂O₃ Rh/Dy₂O₃ Ho₂O₃ Ru/Ho₂O₃ Sr/Ho₂O₃ Zr/Ho₂O₃ Ta/Ho₂O₃ Rh/Ho₂O₃ Er₂O₃ Ru/Er₂O₃ Sr/Er₂O₃ Zr/Er₂O₃ Ta/Er₂O₃ Rh/Er₂O₃ Tm₂O₃ Ru/Tm₂O₃ Sr/Tm₂O₃ Zr/Tm₂O₃ Ta/Tm₂O₃ Rh/Tm₂O₃ Yb₂O₃ Ru/Yb₂O₃ Sr/Yb₂O₃ Zr/Yb₂O₃ Ta/Yb₂O₃ Rh/Yb₂O₃ Lu₂O₃ Ru/Lu₂O₃ Sr/Lu₂O₃ Zr/Lu₂O₃ Ta/Lu₂O₃ Rh/Lu₂O₃ Ac₂O₃ Ru/Ac₂O₃ Sr/Ac₂O₃ Zr/Ac₂O₃ Ta/Ac₂O₃ Rh/Ac₂O₃ Th₂O₃ Ru/Th₂O₃ Sr/Th₂O₃ Zr/Th₂O₃ Ta/Th₂O₃ Rh/Th₂O₃ ThO₂ Ru/ThO₂ Sr/ThO₂ Zr/ThO₂ Ta/ThO₂ Rh/ThO₂ Pa₂O₃ Ru/Pa₂O₃ Sr/Pa₂O₃ Zr/Pa₂O₃ Ta/Pa₂O₃ Rh/Pa₂O₃ PaO₂ Ru/PaO₂ Sr/PaO₂ Zr/PaO₂ Ta/PaO₂ Rh/PaO₂ TiO₂ Ru/TiO₂ Sr/TiO₂ Zr/TiO₂ Ta/TiO₂ Rh/TiO₂ TiO Ru/TiO Sr/TiO Zr/TiO Ta/TiO Rh/TiO Ti₂O₃ Ru/Ti₂O₃ Sr/Ti₂O₃ Zr/Ti₂O₃ Ta/Ti₂O₃ Rh/Ti₂O₃ Ti₃O Ru/Ti₃O Sr/Ti₃O Zr/Ti₃O Ta/Ti₃O Rh/Ti₃O Ti₂O Ru/Ti₂O Sr/Ti₂O Zr/Ti₂O Ta/Ti₂O Rh/Ti₂O Ti₃O₅ Ru/Ti₃O₅ Sr/Ti₃O₅ Zr/Ti₃O₅ Ta/Ti₃O₅ Rh/Ti₃O₅ Ti₄O₇ Ru/Ti₄O₇ Sr/Ti₄O₇ Zr/Ti₄O₇ Ta/Ti₄O₇ Rh/Ti₄O₇ ZrO₂ Ru/ZrO₂ Sr/ZrO₂ Zr/ZrO₂ Ta/ZrO₂ Rh/ZrO₂ HfO₂ Ru/HfO₂ Sr/HfO₂ Zr/HfO₂ Ta/HfO₂ Rh/HfO₂ VO Ru/VO Sr/VO Zr/VO Ta/VO Rh/VO V₂O₃ Ru/V₂O₃ Sr/V₂O₃ Zr/V₂O₃ Ta/V₂O₃ Rh/V₂O₃ VO₂ Ru/VO₂ Sr/VO₂ Zr/VO₂ Ta/VO₂ Rh/VO₂ V₂O₅ Ru/V₂O₅ Sr/V₂O₅ Zr/V₂O₅ Ta/V₂O₅ Rh/V₂O₅ V₃O₇ Ru/V₃O₇ Sr/V₃O₇ Zr/V₃O₇ Ta/V₃O₇ Rh/V₃O₇ V₄O₉ Ru/V₄O₉ Sr/V₄O₉ Zr/V₄O₉ Ta/V₄O₉ Rh/V₄O₉ V₆O₁₃ Ru/V₆O₁₃ Sr/V₆O₁₃ Zr/V₆O₁₃ Ta/V₆O₁₃ Rh/V₆O₁₃ NbO Ru/NbO Sr/NbO Zr/NbO Ta/NbO Rh/NbO NbO₂ Ru/NbO₂ Sr/NbO₂ Zr/NbO₂ Ta/NbO₂ Rh/NbO₂ Nb₂O₅ Ru/Nb₂O₅ Sr/Nb₂O₅ Zr/Nb₂O₅ Ta/Nb₂O₅ Rh/Nb₂O₅ Nb₈O₁₉ Ru/Nb₈O₁₉ Sr/Nb₈O₁₉ Zr/Nb₈O₁₉ Ta/Nb₈O₁₉ Rh/Nb₈O₁₉ Nb₁₆O₃₈ Ru/Nb₁₆O₃₈ Sr/Nb₁₆O₃₈ Zr/Nb₁₆O₃₈ Ta/Nb₁₆O₃₈ Rh/Nb₁₆O₃₈ Nb₁₂O₂₉ Ru/Nb₁₂O₂₉ Sr/Nb₁₂O₂₉ Zr/Nb₁₂O₂₉ Ta/Nb₁₂O₂₉ Rh/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Ru/Nb₄₇O₁₁₆ Sr/Nb₄₇O₁₁₆ Zr/Nb₄₇O₁₁₆ Ta/Nb₄₇O₁₁₆ Rh/Nb₄₇O₁₁₆ Ta₂O₅ Ru/Ta₂O₅ Sr/Ta₂O₅ Zr/Ta₂O₅ Ta/Ta₂O₅ Rh/Ta₂O₅ CrO Ru/CrO Sr/CrO Zr/CrO Ta/CrO Rh/CrO Cr₂O₃ Ru/Cr₂O₃ Sr/Cr₂O₃ Zr/Cr₂O₃ Ta/Cr₂O₃ Rh/Cr₂O₃ CrO₂ Ru/CrO₂ Sr/CrO₂ Zr/CrO₂ Ta/CrO₂ Rh/CrO₂ CrO₃ Ru/CrO₃ Sr/CrO₃ Zr/CrO₃ Ta/CrO₃ Rh/CrO₃ Cr₈O₂₁ Ru/Cr₈O₂₁ Sr/Cr₈O₂₁ Zr/Cr₈O₂₁ Ta/Cr₈O₂₁ Rh/Cr₈O₂₁ MoO₂ Ru/MoO₂ Sr/MoO₂ Zr/MoO₂ Ta/MoO₂ Rh/MoO₂ MoO₃ Ru/MoO₃ Sr/MoO₃ Zr/MoO₃ Ta/MoO₃ Rh/MoO₃ W₂O₃ Ru/W₂O₃ Sr/W₂O₃ Zr/W₂O₃ Ta/W₂O₃ Rh/W₂O₃ WoO₂ Ru/WoO₂ Sr/WoO₂ Zr/WoO₂ Ta/WoO₂ Rh/WoO₂ WoO₃ Ru/WoO₃ Sr/WoO₃ Zr/WoO₃ Ta/WoO₃ Rh/WoO₃ MnO Ru/MnO Sr/MnO Zr/MnO Ta/MnO Rh/MnO Mn/Mg/O Ru/Mn/Mg/O Sr/Mn/Mg/O Zr/Mn/Mg/O Ta/Mn/Mg/O Rh/Mn/Mg/O Mn₃O₄ Ru/Mn₃O₄ Sr/Mn₃O₄ Zr/Mn₃O₄ Ta/Mn₃O₄ Rh/Mn₃O₄ Mn₂O₃ Ru/Mn₂O₃ Sr/Mn₂O₃ Zr/Mn₂O₃ Ta/Mn₂O₃ Rh/Mn₂O₃ MnO₂ Ru/MnO₂ Sr/MnO₂ Zr/MnO₂ Ta/MnO₂ Rh/MnO₂ Mn₂O₇ Ru/Mn₂O₇ Sr/Mn₂O₇ Zr/Mn₂O₇ Ta/Mn₂O₇ Rh/Mn₂O₇ ReO₂ Ru/ReO₂ Sr/ReO₂ Zr/ReO₂ Ta/ReO₂ Rh/ReO₂ ReO₃ Ru/ReO₃ Sr/ReO₃ Zr/ReO₃ Ta/ReO₃ Rh/ReO₃ Re₂O₇ Ru/Re₂O₇ Sr/Re₂O₇ Zr/Re₂O₇ Ta/Re₂O₇ Rh/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Ru/Mg₃Mn₃—B₂O₁₀ Sr/Mg₃Mn₃—B₂O₁₀ Zr/Mg₃Mn₃—B₂O₁₀ Ta/Mg₃Mn₃—B₂O₁₀ Rh/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Ru/Mg₃(BO₃)₂ Sr/Mg₃(BO₃)₂ Zr/Mg₃(BO₃)₂ Ta/Mg₃(BO₃)₂ Rh/Mg₃(BO₃)₂ NaWO₄ Ru/NaWO₄ Sr/NaWO₄ Zr/NaWO₄ Ta/NaWO₄ Rh/NaWO₄ Mg₆MnO₈ Ru/Mg₆MnO₈ Sr/Mg₆MnO₈ Zr/Mg₆MnO₈ Ta/Mg₆MnO₈ Rh/Mg₆MnO₈ Mn₂O₄ Ru/Mn₂O₄ Sr/Mn₂O₄ Zr/Mn₂O₄ Ta/Mn₂O₄ Rh/Mn₂O₄ (Li,Mg)₆—MnO₈ Ru/(Li,Mg)₆—MnO₈ Sr/(Li,Mg)₆—MnO₈ Zr/(Li,Mg)₆—MnO₈ Ta/(Li,Mg)₆—MnO₈ Rh/(Li,Mg)₆—MnO₈ Na₄P₂O₇ Ru/Na₄P₂O₇ Sr/Na₄P₂O₇ Zr/Na₄P₂O₇ Ta/Na₄P₂O₇ Rh/Na₄P₂O₇ Mo₂O₈ Ru/Mo₂O₈ Sr/Mo₂O₈ Zr/Mo₂O₈ Ta/Mo₂O₈ Rh/Mo₂O₈ Mn₃O₄/WO₄ Ru/Mn₃O₄/WO₄ Sr/Mn₃O₄/WO₄ Zr/Mn₃O₄/WO₄ Ta/Mn₃O₄/WO₄ Rh/Mn₃O₄/WO₄ Na₂WO₄ Ru/Na₂WO₄ Sr/Na₂WO₄ Zr/Na₂WO₄ Ta/Na₂WO₄ Rh/Na₂WO₄ Zr₂Mo₂O₈ Ru/Zr₂Mo₂O₈ Sr/Zr₂Mo₂O₈ Zr/Zr₂Mo₂O₈ Ta/Zr₂Mo₂O₈ Rh/Zr₂Mo₂O₈ NaMnO₄—/MgO Ru/NaMnO₄—/MgO Sr/NaMnO₄—/MgO Zr/NaMnO₄—/MgO Ta/NaMnO₄—/MgO Rh/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Ru/Na₁₀Mn—W₅O₁₇ Sr/Na₁₀Mn—W₅O₁₇ Zr/Na₁₀Mn—W₅O₁₇ Ta/Na₁₀Mn—W₅O₁₇ Rh/Na₁₀Mn—W₅O₁₇ NW\Dop Au Mo Ni Li₂O Au/Li₂O Mo/Li₂O Ni/Li₂O Na₂O Au/Na₂O Mo/Na₂O Ni/Na₂O K₂O Au/K₂O Mo/K₂O Ni/K₂O Rb₂O Au/Rb₂O Mo/Rb₂O Ni/Rb₂O Cs₂O Au/Cs₂O Mo/Cs₂O Ni/Cs₂O BeO Au/BeO Mo/BeO Ni/BeO MgO Au/MgO Mo/MgO Ni/MgO CaO Au/CaO Mo/CaO Ni/CaO SrO Au/SrO Mo/SrO Ni/SrO BaO Au/BaO Mo/BaO Ni/BaO Sc₂O₃ Au/Sc₂O₃ Mo/Sc₂O₃ Ni/Sc₂O₃ Y₂O₃ Au/Y₂O₃ Mo/Y₂O₃ Ni/Y₂O₃ La₂O₃ Au/La₂O₃ Mo/La₂O₃ Ni/La₂O₃ CeO₂ Au/CeO₂ Mo/CeO₂ Ni/CeO₂ Ce₂O₃ Au/Ce₂O₃ Mo/Ce₂O₃ Ni/Ce₂O₃ Pr₂O₃ Au/Pr₂O₃ Mo/Pr₂O₃ Ni/Pr₂O₃ Nd₂O₃ Au/Nd₂O₃ Mo/Nd₂O₃ Ni/Nd₂O₃ Sm₂O₃ Au/Sm₂O₃ Mo/Sm₂O₃ Ni/Sm₂O₃ Eu₂O₃ Au/Eu₂O₃ Mo/Eu₂O₃ Ni/Eu₂O₃ Gd₂O₃ Au/Gd₂O₃ Mo/Gd₂O₃ Ni/Gd₂O₃ Tb₂O₃ Au/Tb₂O₃ Mo/Tb₂O₃ Ni/Tb₂O₃ TbO₂ Au/TbO₂ Mo/TbO₂ Ni/TbO₂ Tb₆O₁₁ Au/Tb₆O₁₁ Mo/Tb₆O₁₁ Ni/Tb₆O₁₁ Dy₂O₃ Au/Dy₂O₃ Mo/Dy₂O₃ Ni/Dy₂O₃ Ho₂O₃ Au/Ho₂O₃ Mo/Ho₂O₃ Ni/Ho₂O₃ Er₂O₃ Au/Er₂O₃ Mo/Er₂O₃ Ni/Er₂O₃ Tm₂O₃ Au/Tm₂O₃ Mo/Tm₂O₃ Ni/Tm₂O₃ Yb₂O₃ Au/Yb₂O₃ Mo/Yb₂O₃ Ni/Yb₂O₃ Lu₂O₃ Au/Lu₂O₃ Mo/Lu₂O₃ Ni/Lu₂O₃ Ac₂O₃ Au/Ac₂O₃ Mo/Ac₂O₃ Ni/Ac₂O₃ Th₂O₃ Au/Th₂O₃ Mo/Th₂O₃ Ni/Th₂O₃ ThO₂ Au/ThO₂ Mo/ThO₂ Ni/ThO₂ Pa₂O₃ Au/Pa₂O₃ Mo/Pa₂O₃ Ni/Pa₂O₃ PaO₂ Au/PaO₂ Mo/PaO₂ Ni/PaO₂ TiO₂ Au/TiO₂ Mo/TiO₂ Ni/TiO₂ TiO Au/TiO Mo/TiO Ni/TiO Ti₂O₃ Au/Ti₂O₃ Mo/Ti₂O₃ Ni/Ti₂O₃ Ti₃O Au/Ti₃O Mo/Ti₃O Ni/Ti₃O Ti₂O Au/Ti₂O Mo/Ti₂O Ni/Ti₂O Ti₃O₅ Au/Ti₃O₅ Mo/Ti₃O₅ Ni/Ti₃O₅ Ti₄O₇ Au/Ti₄O₇ Mo/Ti₄O₇ Ni/Ti₄O₇ ZrO₂ Au/ZrO₂ Mo/ZrO₂ Ni/ZrO₂ HfO₂ Au/HfO₂ Mo/HfO₂ Ni/HfO₂ VO Au/VO Mo/VO Ni/VO V₂O₃ Au/V₂O₃ Mo/V₂O₃ Ni/V₂O₃ VO₂ Au/VO₂ Mo/VO₂ Ni/VO₂ V₂O₅ Au/V₂O₅ Mo/V₂O₅ Ni/V₂O₅ V₃O₇ Au/V₃O₇ Mo/V₃O₇ Ni/V₃O₇ V₄O₉ Au/V₄O₉ Mo/V₄O₉ Ni/V₄O₉ V₆O₁₃ Au/V₆O₁₃ Mo/V₆O₁₃ Ni/V₆O₁₃ NbO Au/NbO Mo/NbO Ni/NbO NbO₂ Au/NbO₂ Mo/NbO₂ Ni/NbO₂ Nb₂O₅ Au/Nb₂O₅ Mo/Nb₂O₅ Ni/Nb₂O₅ Nb₈O₁₉ Au/Nb₈O₁₉ Mo/Nb₈O₁₉ Ni/Nb₈O₁₉ Nb₁₆O₃₈ Au/Nb₁₆O₃₈ Mo/Nb₁₆O₃₈ Ni/Nb₁₆O₃₈ Nb₁₂O₂₉ Au/Nb₁₂O₂₉ Mo/Nb₁₂O₂₉ Ni/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Au/Nb₄₇O₁₁₆ Mo/Nb₄₇O₁₁₆ Ni/Nb₄₇O₁₁₆ Ta₂O₅ Au/Ta₂O₅ Mo/Ta₂O₅ Ni/Ta₂O₅ CrO Au/CrO Mo/CrO Ni/CrO Cr₂O₃ Au/Cr₂O₃ Mo/Cr₂O₃ Ni/Cr₂O₃ CrO₂ Au/CrO₂ Mo/CrO₂ Ni/CrO₂ CrO₃ Au/CrO₃ Mo/CrO₃ Ni/CrO₃ Cr₈O₂₁ Au/Cr₈O₂₁ Mo/Cr₈O₂₁ Ni/Cr₈O₂₁ MoO₂ Au/MoO₂ Mo/MoO₂ Ni/MoO₂ MoO₃ Au/MoO₃ Mo/MoO₃ Ni/MoO₃ W₂O₃ Au/W₂O₃ Mo/W₂O₃ Ni/W₂O₃ WoO₂ Au/WoO₂ Mo/WoO₂ Ni/WoO₂ WoO₃ Au/WoO₃ Mo/WoO₃ Ni/WoO₃ MnO Au/MnO Mo/MnO Ni/MnO Mn/Mg/O Au/Mn/Mg/O Mo/Mn/Mg/O Ni/Mn/Mg/O Mn₃O₄ Au/Mn₃O₄ Mo/Mn₃O₄ Ni/Mn₃O₄ Mn₂O₃ Au/Mn₂O₃ Mo/Mn₂O₃ Ni/Mn₂O₃ MnO₂ Au/MnO₂ Mo/MnO₂ Ni/MnO₂ Mn₂O₇ Au/Mn₂O₇ Mo/Mn₂O₇ Ni/Mn₂O₇ ReO₂ Au/ReO₂ Mo/ReO₂ Ni/ReO₂ ReO₃ Au/ReO₃ Mo/ReO₃ Ni/ReO₃ Re₂O₇ Au/Re₂O₇ Mo/Re₂O₇ Ni/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Au/Mg₃Mn₃—B₂O₁₀ Mo/Mg₃Mn₃—B₂O₁₀ Ni/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Au/Mg₃(BO₃)₂ Mo/Mg₃(BO₃)₂ Ni/Mg₃(BO₃)₂ NaWO₄ Au/NaWO₄ Mo/NaWO₄ Ni/NaWO₄ Mg₆MnO₈ Au/Mg₆MnO₈ Mo/Mg₆MnO₈ Ni/Mg₆MnO₈ Mn₂O₄ Au/Mn₂O₄ Mo/Mn₂O₄ Ni/Mn₂O₄ (Li,Mg)₆—MnO₈ Au/(Li,Mg)₆—MnO₈ Mo/(Li,Mg)₆—MnO₈ Ni/(Li,Mg)₆—MnO₈ Na₄P₂O₇ Au/Na₄P₂O₇ Mo/Na₄P₂O₇ Ni/Na₄P₂O₇ Mo₂O₈ Au/Mo₂O₈ Mo/Mo₂O₈ Ni/Mo₂O₈ Mn₃O₄/WO₄ Au/Mn₃O₄/WO₄ Mo/Mn₃O₄/WO₄ Ni/Mn₃O₄/WO₄ Na₂WO₄ Au/Na₂WO₄ Mo/Na₂WO₄ Ni/Na₂WO₄ Zr₂Mo₂O₈ Au/Zr₂Mo₂O₈ Mo/Zr₂Mo₂O₈ Ni/Zr₂Mo₂O₈ NaMnO₄—/MgO Au/NaMnO₄—/MgO Mo/NaMnO₄—/MgO Ni/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Au/Na₁₀Mn—W₅O₁₇ Mo/Na₁₀Mn—W₅O₁₇ Ni/Na₁₀Mn—W₅O₁₇

TABLE 7 NANOWIRES (NW) DOPED WITH SPECIFIC DOPANTS (DOP) NW\Dop Co Sb W V Ag Li₂O Co/Li₂O Sb/Li₂O W/Li₂O V/Li₂O Ag/Li₂O Na₂O Co/Na₂O Sb/Na₂O W/Na₂O V/Na₂O Ag/Na₂O K₂O Co/K₂O Sb/K₂O W/K₂O V/K₂O Ag/K₂O Rb₂O Co/Rb₂O Sb/Rb₂O W/Rb₂O V/Rb₂O Ag/Rb₂O Cs₂O Co/Cs₂O Sb/Cs₂O W/Cs₂O V/Cs₂O Ag/Cs₂O BeO Co/BeO Sb/BeO W/BeO V/BeO Ag/BeO MgO Co/MgO Sb/MgO W/MgO V/MgO Ag/MgO CaO Co/CaO Sb/CaO W/CaO V/CaO Ag/CaO SrO Co/SrO Sb/SrO W/SrO V/SrO Ag/SrO BaO Co/BaO Sb/BaO W/BaO V/BaO Ag/BaO Sc₂O₃ Co/Sc₂O₃ Sb/Sc₂O₃ W/Sc₂O₃ V/Sc₂O₃ Ag/Sc₂O₃ Y₂O₃ Co/Y₂O₃ Sb/Y₂O₃ W/Y₂O₃ V/Y₂O₃ Ag/Y₂O₃ La₂O₃ Co/La₂O₃ Sb/La₂O₃ W/La₂O₃ V/La₂O₃ Ag/La₂O₃ CeO₂ Co/CeO₂ Sb/CeO₂ W/CeO₂ V/CeO₂ Ag/CeO₂ Ce₂O₃ Co/Ce₂O₃ Sb/Ce₂O₃ W/Ce₂O₃ V/Ce₂O₃ Ag/Ce₂O₃ Pr₂O₃ Co/Pr₂O₃ Sb/Pr₂O₃ W/Pr₂O₃ V/Pr₂O₃ Ag/Pr₂O₃ Nd₂O₃ Co/Nd₂O₃ Sb/Nd₂O₃ W/Nd₂O₃ V/Nd₂O₃ Ag/Nd₂O₃ Sm₂O₃ Co/Sm₂O₃ Sb/Sm₂O₃ W/Sm₂O₃ V/Sm₂O₃ Ag/Sm₂O₃ Eu₂O₃ Co/Eu₂O₃ Sb/Eu₂O₃ W/Eu₂O₃ V/Eu₂O₃ Ag/Eu₂O₃ Gd₂O₃ Co/Gd₂O₃ Sb/Gd₂O₃ W/Gd₂O₃ V/Gd₂O₃ Ag/Gd₂O₃ Tb₂O₃ Co/Tb₂O₃ Sb/Tb₂O₃ W/Tb₂O₃ V/Tb₂O₃ Ag/Tb₂O₃ TbO₂ Co/TbO₂ Sb/TbO₂ W/TbO₂ V/TbO₂ Ag/TbO₂ Tb₆O₁₁ Co/Tb₆O₁₁ Sb/Tb₆O₁₁ W/Tb₆O₁₁ V/Tb₆O₁₁ Ag/Tb₆O₁₁ Dy₂O₃ Co/Dy₂O₃ Sb/Dy₂O₃ W/Dy₂O₃ V/Dy₂O₃ Ag/Dy₂O₃ Ho₂O₃ Co/Ho₂O₃ Sb/Ho₂O₃ W/Ho₂O₃ V/Ho₂O₃ Ag/Ho₂O₃ Er₂O₃ Co/Er₂O₃ Sb/Er₂O₃ W/Er₂O₃ V/Er₂O₃ Ag/Er₂O₃ Tm₂O₃ Co/Tm₂O₃ Sb/Tm₂O₃ W/Tm₂O₃ V/Tm₂O₃ Ag/Tm₂O₃ Yb₂O₃ Co/Yb₂O₃ Sb/Yb₂O₃ W/Yb₂O₃ V/Yb₂O₃ Ag/Yb₂O₃ Lu₂O₃ Co/Lu₂O₃ Sb/Lu₂O₃ W/Lu₂O₃ V/Lu₂O₃ Ag/Lu₂O₃ Ac₂O₃ Co/Ac₂O₃ Sb/Ac₂O₃ W/Ac₂O₃ V/Ac₂O₃ Ag/Ac₂O₃ Th₂O₃ Co/Th₂O₃ Sb/Th₂O₃ W/Th₂O₃ V/Th₂O₃ Ag/Th₂O₃ ThO₂ Co/ThO₂ Sb/ThO₂ W/ThO₂ V/ThO₂ Ag/ThO₂ Pa₂O₃ Co/Pa₂O₃ Sb/Pa₂O₃ W/Pa₂O₃ V/Pa₂O₃ Ag/Pa₂O₃ PaO₂ Co/PaO₂ Sb/PaO₂ W/PaO₂ V/PaO₂ Ag/PaO₂ TiO₂ Co/TiO₂ Sb/TiO₂ W/TiO₂ V/TiO₂ Ag/TiO₂ TiO Co/TiO Sb/TiO W/TiO V/TiO Ag/TiO Ti₂O₃ Co/Ti₂O₃ Sb/Ti₂O₃ W/Ti₂O₃ V/Ti₂O₃ Ag/Ti₂O₃ Ti₃O Co/Ti₃O Sb/Ti₃O W/Ti₃O V/Ti₃O Ag/Ti₃O Ti₂O Co/Ti₂O Sb/Ti₂O W/Ti₂O V/Ti₂O Ag/Ti₂O Ti₃O₅ Co/Ti₃O₅ Sb/Ti₃O₅ W/Ti₃O₅ V/Ti₃O₅ Ag/Ti₃O₅ Ti₄O₇ Co/Ti₄O₇ Sb/Ti₄O₇ W/Ti₄O₇ V/Ti₄O₇ Ag/Ti₄O₇ ZrO₂ Co/ZrO₂ Sb/ZrO₂ W/ZrO₂ V/ZrO₂ Ag/ZrO₂ HfO₂ Co/HfO₂ Sb/HfO₂ W/HfO₂ V/HfO₂ Ag/HfO₂ VO Co/VO Sb/VO W/VO V/VO Ag/VO V₂O₃ Co/V₂O₃ Sb/V₂O₃ W/V₂O₃ V/V₂O₃ Ag/V₂O₃ VO₂ Co/VO₂ Sb/VO₂ W/VO₂ V/VO₂ Ag/VO₂ V₂O₅ Co/V₂O₅ Sb/V₂O₅ W/V₂O₅ V/V₂O₅ Ag/V₂O₅ V₃O₇ Co/V₃O₇ Sb/V₃O₇ W/V₃O₇ V/V₃O₇ Ag/V₃O₇ V₄O₉ Co/V₄O₉ Sb/V₄O₉ W/V₄O₉ V/V₄O₉ Ag/V₄O₉ V₆O₁₃ Co/V₆O₁₃ Sb/V₆O₁₃ W/V₆O₁₃ V/V₆O₁₃ Ag/V₆O₁₃ NbO Co/NbO Sb/NbO W/NbO V/NbO Ag/NbO NbO₂ Co/NbO₂ Sb/NbO₂ W/NbO₂ V/NbO₂ Ag/NbO₂ Nb₂O₅ Co/Nb₂O₅ Sb/Nb₂O₅ W/Nb₂O₅ V/Nb₂O₅ Ag/Nb₂O₅ Nb₈O₁₉ Co/Nb₈O₁₉ Sb/Nb₈O₁₉ W/Nb₈O₁₉ V/Nb₈O₁₉ Ag/Nb₈O₁₉ Nb₁₆O₃₈ Co/Nb₁₆O₃₈ Sb/Nb₁₆O₃₈ W/Nb₁₆O₃₈ V/Nb₁₆O₃₈ Ag/Nb₁₆O₃₈ Nb₁₂O₂₉ Co/Nb₁₂O₂₉ Sb/Nb₁₂O₂₉ W/Nb₁₂O₂₉ V/Nb₁₂O₂₉ Ag/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Co/Nb₄₇O₁₁₆ Sb/Nb₄₇O₁₁₆ W/Nb₄₇O₁₁₆ V/Nb₄₇O₁₁₆ Ag/Nb₄₇O₁₁₆ Ta₂O₅ Co/Ta₂O₅ Sb/Ta₂O₅ W/Ta₂O₅ V/Ta₂O₅ Ag/Ta₂O₅ CrO Co/CrO Sb/CrO W/CrO V/CrO Ag/CrO Cr₂O₃ Co/Cr₂O₃ Sb/Cr₂O₃ W/Cr₂O₃ V/Cr₂O₃ Ag/Cr₂O₃ CrO₂ Co/CrO₂ Sb/CrO₂ W/CrO₂ V/CrO₂ Ag/CrO₂ CrO₃ Co/CrO₃ Sb/CrO₃ W/CrO₃ V/CrO₃ Ag/CrO₃ Cr₈O₂₁ Co/Cr₈O₂₁ Sb/Cr₈O₂₁ W/Cr₈O₂₁ V/Cr₈O₂₁ Ag/Cr₈O₂₁ MoO₂ Co/MoO₂ Sb/MoO₂ W/MoO₂ V/MoO₂ Ag/MoO₂ MoO₃ Co/MoO₃ Sb/MoO₃ W/MoO₃ V/MoO₃ Ag/MoO₃ W₂O₃ Co/W₂O₃ Sb/W₂O₃ W/W₂O₃ V/W₂O₃ Ag/W₂O₃ WoO₂ Co/WoO₂ Sb/WoO₂ W/WoO₂ V/WoO₂ Ag/WoO₂ WoO₃ Co/WoO₃ Sb/WoO₃ W/WoO₃ V/WoO₃ Ag/WoO₃ MnO Co/MnO Sb/MnO W/MnO V/MnO Ag/MnO Mn/Mg/O Co/Mn/Mg/O Sb/Mn/Mg/O W/Mn/Mg/O V/Mn/Mg/O Ag/Mn/Mg/O Mn₃O₄ Co/Mn₃O₄ Sb/Mn₃O₄ W/Mn₃O₄ V/Mn₃O₄ Ag/Mn₃O₄ Mn₂O₃ Co/Mn₂O₃ Sb/Mn₂O₃ W/Mn₂O₃ V/Mn₂O₃ Ag/Mn₂O₃ MnO₂ Co/MnO₂ Sb/MnO₂ W/MnO₂ V/MnO₂ Ag/MnO₂ Mn₂O₇ Co/Mn₂O₇ Sb/Mn₂O₇ W/Mn₂O₇ V/Mn₂O₇ Ag/Mn₂O₇ ReO₂ Co/ReO₂ Sb/ReO₂ W/ReO₂ V/ReO₂ Ag/ReO₂ ReO₃ Co/ReO₃ Sb/ReO₃ W/ReO₃ V/ReO₃ Ag/ReO₃ Re₂O₇ Co/Re₂O₇ Sb/Re₂O₇ W/Re₂O₇ V/Re₂O₇ Ag/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Co/Mg₃Mn₃—B₂O₁₀ Sb/Mg₃Mn₃—B₂O₁₀ W/Mg₃Mn₃—B₂O₁₀ V/Mg₃Mn₃—B₂O₁₀ Ag/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Co/Mg₃(BO₃)₂ Sb/Mg₃(BO₃)₂ W/Mg₃(BO₃)₂ V/Mg₃(BO₃)₂ Ag/Mg₃(BO₃)₂ NaWO₄ Co/NaWO₄ Sb/NaWO₄ W/NaWO₄ V/NaWO₄ Ag/NaWO₄ Mg₆MnO₈ Co/Mg₆MnO₈ Sb/Mg₆MnO₈ W/Mg₆MnO₈ V/Mg₆MnO₈ Ag/Mg₆MnO₈ Mn₂O₄ Co/Mn₂O₄ Sb/Mn₂O₄ W/Mn₂O₄ V/Mn₂O₄ Ag/Mn₂O₄ (Li,Mg)₆—MnO₈ Co/(Li,Mg)₆—MnO₈ Sb/(Li,Mg)₆—MnO₈ W/(Li,Mg)₆—MnO₈ V/(Li,Mg)₆—MnO₈ Ag/(Li,Mg)₆—MnO₈ Na₄P₂O₇ Co/Na₄P₂O₇ Sb/Na₄P₂O₇ W/Na₄P₂O₇ V/Na₄P₂O₇ Ag/Na₄P₂O₇ Mo₂O₈ Co/Mo₂O₈ Sb/Mo₂O₈ W/Mo₂O₈ V/Mo₂O₈ Ag/Mo₂O₈ Mn₃O₄/WO₄ Co/Mn₃O₄/WO₄ Sb/Mn₃O₄/WO₄ W/Mn₃O₄/WO₄ V/Mn₃O₄/WO₄ Ag/Mn₃O₄/WO₄ Na₂WO₄ Co/Na₂WO₄ Sb/Na₂WO₄ W/Na₂WO₄ V/Na₂WO₄ Ag/Na₂WO₄ Zr₂Mo₂O₈ Co/Zr₂Mo₂O₈ Sb/Zr₂Mo₂O₈ W/Zr₂Mo₂O₈ V/Zr₂Mo₂O₈ Ag/Zr₂Mo₂O₈ NaMnO₄—/MgO Co/NaMnO₄—/MgO Sb/NaMnO₄—/MgO W/NaMnO₄—/MgO V/NaMnO₄—/MgO Ag/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Co/Na₁₀Mn—W₅O₁₇ Sb/Na₁₀Mn—W₅O₁₇ W/Na₁₀Mn—W₅O₁₇ V/Na₁₀Mn—W₅O₁₇ Ag/Na₁₀Mn—W₅O₁₇ NW\Dop Te Pd Ir Li₂O Te/Li₂O Pd/Li₂O Ir/Li₂O Na₂O Te/Na₂O Pd/Na₂O Ir/Na₂O K₂O Te/K₂O Pd/K₂O Ir/K₂O Rb₂O Te/Rb₂O Pd/Rb₂O Ir/Rb₂O Cs₂O Te/Cs₂O Pd/Cs₂O Ir/Cs₂O BeO Te/BeO Pd/BeO Ir/BeO MgO Te/MgO Pd/MgO Ir/MgO CaO Te/CaO Pd/CaO Ir/CaO SrO Te/SrO Pd/SrO Ir/SrO BaO Te/BaO Pd/BaO Ir/BaO Sc₂O₃ Te/Sc₂O₃ Pd/Sc₂O₃ Ir/Sc₂O₃ Y₂O₃ Te/Y₂O₃ Pd/Y₂O₃ Ir/Y₂O₃ La₂O₃ Te/La₂O₃ Pd/La₂O₃ Ir/La₂O₃ CeO₂ Te/CeO₂ Pd/CeO₂ Ir/CeO₂ Ce₂O₃ Te/Ce₂O₃ Pd/Ce₂O₃ Ir/Ce₂O₃ Pr₂O₃ Te/Pr₂O₃ Pd/Pr₂O₃ Ir/Pr₂O₃ Nd₂O₃ Te/Nd₂O₃ Pd/Nd₂O₃ Ir/Nd₂O₃ Sm₂O₃ Te/Sm₂O₃ Pd/Sm₂O₃ Ir/Sm₂O₃ Eu₂O₃ Te/Eu₂O₃ Pd/Eu₂O₃ Ir/Eu₂O₃ Gd₂O₃ Te/Gd₂O₃ Pd/Gd₂O₃ Ir/Gd₂O₃ Tb₂O₃ Te/Tb₂O₃ Pd/Tb₂O₃ Ir/Tb₂O₃ TbO₂ Te/TbO₂ Pd/TbO₂ Ir/TbO₂ Tb₆O₁₁ Te/Tb₆O₁₁ Pd/Tb₆O₁₁ Ir/Tb₆O₁₁ Dy₂O₃ Te/Dy₂O₃ Pd/Dy₂O₃ Ir/Dy₂O₃ Ho₂O₃ Te/Ho₂O₃ Pd/Ho₂O₃ Ir/Ho₂O₃ Er₂O₃ Te/Eu₂O₃ Pd/Er₂O₃ Ir/Er₂O₃ Tm₂O₃ Te/Tm₂O₃ Pd/Tm₂O₃ Ir/Tm₂O₃ Yb₂O₃ Te/Yb₂O₃ Pd/Yb₂O₃ Ir/Yb₂O₃ Lu₂O₃ Te/Lu₂O₃ Pd/Lu₂O₃ Ir/Lu₂O₃ Ac₂O₃ Te/Ac₂O₃ Pd/Ac₂O₃ Ir/Ac₂O₃ Th₂O₃ Te/Th₂O₃ Pd/Th₂O₃ Ir/Th₂O₃ ThO₂ Te/ThO₂ Pd/ThO₂ Ir/ThO₂ Pa₂O₃ Te/Pa₂O₃ Pd/Pa₂O₃ Ir/Pa₂O₃ PaO₂ Te/PaO₂ Pd/PaO₂ Ir/PaO₂ TiO₂ Te/TiO₂ Pd/TiO₂ Ir/TiO₂ TiO Te/TiO Pd/TiO Ir/TiO Ti₂O₃ Te/Ti₂O₃ Pd/Ti₂O₃ Ir/Ti₂O₃ Ti₃O Te/Ti₃O Pd/Ti₃O Ir/Ti₃O Ti₂O Te/Ti₂O Pd/Ti₂O Ir/Ti₂O Ti₃O₅ Te/Ti₃O₅ Pd/Ti₃O₅ Ir/Ti₃O₅ Ti₄O₇ Te/Ti₄O₇ Pd/Ti₄O₇ Ir/Ti₄O₇ ZrO₂ Te/ZrO₂ Pd/ZrO₂ Ir/ZrO₂ HfO₂ Te/HfO₂ Pd/HfO₂ Ir/HfO₂ VO Te/VO Pd/VO Ir/VO V₂O₃ Te/V₂O₃ Pd/V₂O₃ Ir/V₂O₃ VO₂ Te/VO₂ Pd/VO₂ Ir/VO₂ V₂O₅ Te/V₂O₅ Pd/V₂O₅ Ir/V₂O₅ V₃O₇ Te/V₃O₇ Pd/V₃O₇ Ir/V₃O₇ V₄O₉ Te/V₄O₉ Pd/V₄O₉ Ir/V₄O₉ V₆O₁₃ Te/V₆O₁₃ Pd/V₆O₁₃ Ir/V₆O₁₃ NbO Te/NbO Pd/NbO Ir/NbO NbO₂ Te/NbO₂ Pd/NbO₂ Ir/NbO₂ Nb₂O₅ Te/Nb₂O₅ Pd/Nb₂O₅ Ir/Nb₂O₅ Nb₈O₁₉ Te/Nb₈O₁₉ Pd/Nb₈O₁₉ Ir/Nb₈O₁₉ Nb₁₆O₃₈ Te/Nb₁₆O₃₈ Pd/Nb₁₆O₃₈ Ir/Nb₁₆O₃₈ Nb₁₂O₂₉ Te/Nb₁₂O₂₉ Pd/Nb₁₂O₂₉ Ir/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Te/Nb₄₇O₁₁₆ Pd/Nb₄₇O₁₁₆ Ir/Nb₄₇O₁₁₆ Ta₂O₅ Te/Ta₂O₅ Pd/Ta₂O₅ Ir/Ta₂O₅ CrO Te/CrO Pd/CrO Ir/CrO Cr₂O₃ Te/Cr₂O₃ Pd/Cr₂O₃ Ir/Cr₂O₃ CrO₂ Te/CrO₂ Pd/CrO₂ Ir/CrO₂ CrO₃ Te/CrO₃ Pd/CrO₃ Ir/CrO₃ Cr₈O₂₁ Te/Cr₈O₂₁ Pd/Cr₈O₂₁ Ir/Cr₈O₂₁ MoO₂ Te/MoO₂ Pd/MoO₂ Ir/MoO₂ MoO₃ Te/MoO₃ Pd/MoO₃ Ir/MoO₃ W₂O₃ Te/W₂O₃ Pd/W₂O₃ Ir/W₂O₃ WoO₂ Te/WoO₂ Pd/WoO₂ Ir/WoO₂ WoO₃ Te/WoO₃ Pd/WoO₃ Ir/WoO₃ MnO Te/MnO Pd/MnO Ir/MnO Mn/Mg/O Te/Mn/Mg/O Pd/Mn/Mg/O Ir/Mn/Mg/O Mn₃O₄ Te/Mn₃O₄ Pd/Mn₃O₄ Ir/Mn₃O₄ Mn₂O₃ Te/Mn₂O₃ Pd/Mn₂O₃ Ir/Mn₂O₃ MnO₂ Te/MnO₂ Pd/MnO₂ Ir/MnO₂ Mn₂O₇ Te/Mn₂O₇ Pd/Mn₂O₇ Ir/Mn₂O₇ ReO₂ Te/ReO₂ Pd/ReO₂ Ir/ReO₂ ReO₃ Te/ReO₃ Pd/ReO₃ Ir/ReO₃ Re₂O₇ Te/Re₂O₇ Pd/Re₂O₇ Ir/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Te/Mg₃Mn₃—B₂O₁₀ Pd/Mg₃Mn₃—B₂O₁₀ Ir/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Te/Mg₃(BO₃)₂ Pd/Mg₃(BO₃)₂ Ir/Mg₃(BO₃)₂ NaWO₄ Te/NaWO₄ Pd/NaWO₄ Ir/NaWO₄ Mg₆MnO₈ Te/Mg₆MnO₈ Pd/Mg₆MnO₈ Ir/Mg₆MnO₈ Mn₂O₄ Te/Mn₂O₄ Pd/Mn₂O₄ Ir/Mn₂O₄ (Li,Mg)₆—MnO₈ Te/(Li,Mg)₆—MnO₈ Pd/(Li,Mg)₆—MnO₈ Ir/(Li,Mg)₆—MnO₈ Na₄P₂O₇ Te/Na₄P₂O₇ Pd/Na₄P₂O₇ Ir/Na₄P₂O₇ Mo₂O₈ Te/Mo₂O₈ Pd/Mo₂O₈ Ir/Mo₂O₈ Mn₃O₄/WO₄ Te/Mn₃O₄/WO₄ Pd/Mn₃O₄/WO₄ Ir/Mn₃O₄/WO₄ Na₂WO₄ Te/Na₂WO₄ Pd/Na₂WO₄ Ir/Na₂WO₄ Zr₂Mo₂O₈ Te/Zr₂Mo₂O₈ Pd/Zr₂Mo₂O₈ Ir/Zr₂Mo₂O₈ NaMnO₄—/MgO Te/NaMnO₄—/MgO Pd/NaMnO₄—/MgO Ir/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Te/Na₁₀Mn—W₅O₁₇ Pd/Na₁₀Mn—W₅O₁₇ Ir/Na₁₀Mn—W₅O₁₇

TABLE 8 NANOWIRES (NW) DOPED WITH SPECIFIC DOPANTS (DOP) NW\Dop Mn Ti Li₂O Mn/Li₂O Ti/Li₂O Na₂O Mn/Na₂O Ti/Na₂O K₂O Mn/K₂O Ti/K₂O Rb₂O Mn/Rb₂O Ti/Rb₂O Cs₂O Mn/Cs₂O Ti/Cs₂O BeO Mn/BeO Ti/BeO MgO Mn/MgO Ti/MgO CaO Mn/CaO Ti/CaO SrO Mn/SrO Ti/SrO BaO Mn/BaO Ti/BaO Sc₂O₃ Mn/Sc₂O₃ Ti/Sc₂O₃ Y₂O₃ Mn/Y₂O₃ Ti/Y₂O₃ La₂O₃ Mn/La₂O₃ Ti/La₂O₃ CeO₂ Mn/CeO₂ Ti/CeO₂ Ce₂O₃ Mn/Ce₂O₃ Ti/Ce₂O₃ Pr₂O₃ Mn/Pr₂O₃ Ti/Pr₂O₃ Nd₂O₃ Mn/Nd₂O₃ Ti/Nd₂O₃ Sm₂O₃ Mn/Sm₂O₃ Ti/Sm₂O₃ Eu₂O₃ Mn/Eu₂O₃ Ti/Eu₂O₃ Gd₂O₃ Mn/Gd₂O₃ Ti/Gd₂O₃ Tb₂O₃ Mn/Tb₂O₃ Ti/Tb₂O₃ TbO₂ Mn/TbO₂ Ti/TbO₂ Tb₆O₁₁ Mn/Tb₆O₁₁ Ti/Tb₆O₁₁ Dy₂O₃ Mn/Dy₂O₃ Ti/Dy₂O₃ Ho₂O₃ Mn/Ho₂O₃ Ti/Ho₂O₃ Er₂O₃ Mn/Er₂O₃ Ti/Er₂O₃ Tm₂O₃ Mn/Tm₂O₃ Ti/Tm₂O₃ Yb₂O₃ Mn/Yb₂O₃ Ti/Yb₂O₃ Lu₂O₃ Mn/Lu₂O₃ Ti/Lu₂O₃ Ac₂O₃ Mn/Ac₂O₃ Ti/Ac₂O₃ Th₂O₃ Mn/Th₂O₃ Ti/Th₂O₃ ThO₂ Mn/ThO₂ Ti/ThO₂ Pa₂O₃ Mn/Pa₂O₃ Ti/Pa₂O₃ PaO₂ Mn/PaO₂ Ti/PaO₂ TiO₂ Mn/TiO₂ Ti/TiO₂ TiO Mn/TiO Ti/TiO Ti₂O₃ Mn/Ti₂O₃ Ti/Ti₂O₃ Ti₃O Mn/Ti₃O Ti/Ti₃O Ti₂O Mn/Ti₂O Ti/Ti₂O Ti₃O₅ Mn/Ti₃O₅ Ti/Ti₃O₅ Ti₄O₇ Mn/Ti₄O₇ Ti/Ti₄O₇ ZrO₂ Mn/ZrO₂ Ti/ZrO₂ HfO₂ Mn/HfO₂ Ti/HfO₂ VO Mn/VO Ti/VO V₂O₃ Mn/V₂O₃ Ti/V₂O₃ VO₂ Mn/VO₂ Ti/VO₂ V₂O₅ Mn/V₂O₅ Ti/V₂O₅ V₃O₇ Mn/V₃O₇ Ti/V₃O₇ V₄O₉ Mn/V₄O₉ Ti/V₄O₉ V₆O₁₃ Mn/V₆O₁₃ Ti/V₆O₁₃ NbO Mn/NbO Ti/NbO NbO₂ Mn/NbO₂ Ti/NbO₂ Nb₂O₅ Mn/Nb₂O₅ Ti/Nb₂O₅ Nb₈O₁₉ Mn/Nb₈O₁₉ Ti/Nb₈O₁₉ Nb₁₆O₃₈ Mn/Nb₁₆O₃₈ Ti/Nb₁₆O₃₈ Nb₁₂O₂₉ Mn/Nb₁₂O₂₉ Ti/Nb₁₂O₂₉ Nb₄₇O₁₁₆ Mn/Nb₄₇O₁₁₆ Ti/Nb₄₇O₁₁₆ Ta₂O₅ Mn/Ta₂O₅ Ti/Ta₂O₅ CrO Mn/CrO Ti/CrO Cr₂O₃ Mn/Cr₂O₃ Ti/Cr₂O₃ CrO₂ Mn/CrO₂ Ti/CrO₂ CrO₃ Mn/CrO₃ Ti/CrO₃ Cr₈O₂₁ Mn/Cr₈O₂₁ Ti/Cr₈O₂₁ MoO₂ Mn/MoO₂ Ti/MoO₂ MoO₃ Mn/MoO₃ Ti/MoO₃ W₂O₃ Mn/W₂O₃ Ti/W₂O₃ WoO₂ Mn/WoO₂ Ti/WoO₂ WoO₃ Mn/WoO₃ Ti/WoO₃ MnO Mn/MnO Ti/MnO Mn/Mg/O Mn/Mn/Mg/O Ti/Mn/Mg/O Mn₃O₄ Mn/Mn₃O₄ Ti/Mn₃O₄ Mn₂O₃ Mn/Mn₂O₃ Ti/Mn₂O₃ MnO₂ Mn/MnO₂ Ti/MnO₂ Mn₂O₇ Mn/Mn₂O₇ Ti/Mn₂O₇ ReO₂ Mn/ReO₂ Ti/ReO₂ ReO₃ Mn/ReO₃ Ti/ReO₃ Re₂O₇ Mn/Re₂O₇ Ti/Re₂O₇ Mg₃Mn₃—B₂O₁₀ Mn/Mg₃Mn₃—B₂O₁₀ Ti/Mg₃Mn₃—B₂O₁₀ Mg₃(BO₃)₂ Mn/Mg₃(BO₃)₂ Ti/Mg₃(BO₃)₂ NaWO₄ Mn/NaWO₄ Ti/NaWO₄ Mg₆MnO₈ Mn/Mg₆MnO₈ Ti/Mg₆MnO₈ Mn₂O₄ Mn/Mn₂O₄ Ti/Mn₂O₄ (Li,Mg)₆—MnO₈ Mn/(Li,Mg)₆—MnO₈ Mn/(Li,Mg)₆—MnO₈ Na₄P₂O₇ Mn/Na₄P₂O₇ Ti/Na₄P₂O₇ Mo₂O₈ Mn/Mo₂O₈ Ti/Mo₂O₈ Mn₃O₄/WO₄ Mn/Mn₃O₄/WO₄ Ti/Mn₃O₄/WO₄ Na₂WO₄ Mn/Na₂WO₄ Ti/Na₂WO₄ Zr₂Mo₂O₈ Mn/Zr₂Mo₂O₈ Ti/Zr₂Mo₂O₈ NaMnO₄—/MgO Mn/NaMnO₄—/MgO Ti/NaMnO₄—/MgO Na₁₀Mn—W₅O₁₇ Mn/Na₁₀Mn—W₅O₁₇ Ti/Na₁₀Mn—W₅O₁₇

As used in Tables 1-8 and throughout the specification, a nanowire composition represented by E¹/E²/E³,etc., wherein E¹, E² and E³ are each independently an element or a compound comprising one or more elements, refers to a nanowire composition comprised of a mixture of E¹, E² and E³. E¹/E²/E³, etc. are not necessarily present in equal amounts and need not form a bond with one another. For example, a nanowire comprising Li/MgO refers to a nanowire comprising Li and MgO, for example, Li/MgO may refer to a MgO nanowire doped with Li. By way of another example, a nanowire comprising NaMnO₄/MgO refers to a nanowire comprised of a mixture of NaMnO₄ and MgO. Dopants may be added in suitable form. For example in a lithium doped magnesium oxide nanowire (Li/MgO), the Li dopant can be incorporated in the form of Li₂O, Li₂CO₃, LiOH, or other suitable forms. Li may be fully incorporated in the MgO crystal lattice→(e.g., (Li,Mg)O) as well. Dopants for other nanowires may be incorporated analogously.

In some more specific embodiments, the dopant is selected from Li, Ba and Sr. In other specific embodiments, the nanowires comprise Li/MgO, Ba/MgO, Sr/La₂O₃, Ba/La₂O₃, Mn/Na₂WO₄, Mn₂O₃/Na₂WO₄, Mn₃O₄/Na₂WO₄, Mg₆MnO₈, Li/B/Mg₆MnO₈, Na/B/Mg₆MnO₈, Zr₂Mo₂O₈ or NaMnO₄/MgO.

In some other specific embodiments, the nanowire comprises a mixed oxide of Mn and Mg with or without B and with or without Li. Additional dopants for such nanowires may comprise doping elements selected from Group 1 and 2 and groups 7-13. The dopants may be present as single dopants or in combination with other dopants. In certain specific embodiments of nanowires comprising a mixed oxide of Mn and Mg with or without B and with or without Li., the dopant comprises a combination of elements from group 1 and group 8-11.

Nanowires comprising mixed oxides of Mn and Mg are well suited for incorporation of dopants because magnesium atoms can be easily substituted by other atoms as long as their size is comparable with magnesium. A family of “doped” Mg₆MnO₈ compounds with the composition M_((x))Mg_((6-x))MnO₈, wherein each M is independently a dopant as defined herein and x is 0 to 6, can thus be created. The oxidation state of Mn can be tuned by selecting different amounts (i.e., different values of x) of M with different oxidation states, for example Li_((x))Mg_((6-x))MnO₈ would contain a mixture of Mn(IV) and Mn(V) with x<1 and a mixture that may include Mn(V), Mn(VI), Mn(VII) with x>1. The maximum value of x depends on the ability of a particular atom M to be incorporated in the Mg₆MnO₈ crystal structure and therefore varies depending on M. It is believed that the ability to tune the manganese oxidation state as described above could have advantageous effect on the catalytic activity of the disclosed nanowires.

Examples of nanowires comprising Li/Mn/Mg/B and an additional dopant include; Li/Mn/Mg/B doped with Co; Li/Mn/Mg/B doped with Na, Li/Mn/Mg/B doped with Be; Li/Mn/Mg/B doped with Al; Li/Mn/Mg/B doped with Hf; Li/Mn/Mg/B doped with Zr; Li/Mn/Mg/B doped with Zn; Li/Mn/Mg/B doped with Rh and Li/Mn/Mg/B doped with Ga. Nanowires comprising Li/Mn/Mg/B doped with different combinations of these dopants are also provided. For example, in some embodiments the Li/Mn/Mg/B nanowires are doped with Na and Co. In other embodiments, the Li/Mn/Mg/B nanowires are doped with Ga and Na.

In other embodiments, nanowires comprising Mn/W with or without dopants are provided. For example, the present inventors have found through high throughput testing that nanowires comprising Mn/W and various dopants are good catalysts in the OCM reaction. Accordingly, in some embodiments, the Mn/W nanowires are doped with Ba. In other embodiments, the Mn/W nanowires are doped with Be. In yet other embodiments, the Mn/W nanowires are doped with Te.

In any of the above embodiments, the Mn/W nanowires may comprise a SiO₂ support. Alternatively, the use of different supports such as ZrO₂, HfO₂ and ln₂O₃ in any of the above embodiments has been shown to promote OCM activity at reduced temperature compared to the same catalyst supported on silica with limited reduction in selectivity.

Nanowires comprising rare earth oxides or Yttria doped with various elements are also effective catalysts in the OCM reaction. In certain specific embodiments, the rare earth oxide or oxy-hydroxide can be any rare earth, preferably La, Nd, Eu, Sm, Yb, Gd. In certain embodiments of the nanowires comprising rare earth elements or yttria, the dopant comprises alkali earth (group 2) elements. The degree of effectiveness of a particular dopant is a function of the rare earth used and the concentration of the alkali earth dopant. In addition to Alkali earth elements, further embodiments of the rare earth or yttria nanowires include embodiments wherein the nanowires comprise alkali elements as dopants which further promote the selectivity of the OCM catalytic activity of the doped material. In yet other embodiments of the foregoing, the nanowires comprise both an alkali element and alkali earth element as dopant. In still further embodiments, an additional dopant can be selected from an additional rare earth and groups 3, 4, 8, 9, 10, 13, 14.

The foregoing rare earth or yttria catalyst may be doped prior to, or after formation of the rare earth or yttria oxide. In one, the rare earth or yttria salt is mixed with the precursor salt to form a solution or a slurry which is dried and then calcined in a range of 400° C. to 900° C., or between 500° C. and 700° C. In another embodiment, the rare earth or yttria oxide is formed first through calcination of a rare earth or yttria salt and then contacted with a solution comprising the doping element prior to drying and calcination between 300° C. and 800° C., or between 400° C. and 700° C.

In other embodiments, the nanowires comprise La₂O₃ or LaO_(y)(OH)_(x), wherein y ranges from 0 to 1.5, x ranges from 0 to 3 and 2y+x=3, doped with Na, Mg, Ca, Sr, Ga, Sc, Y, Zr. In, Nd, Eu, Sm ,Ce, Gd or combinations thereof. In yet further embodiments, the La₂O₃ or LaO_(y)(OH)_(x) nanowires are doped with binary dopant combinations, for example Eu/Na; Eu/Gd; Ca/Na; Eu/Sm; Eu/Sr; Mg/Sr; Ce/Mg; Gd/Sm, Mg/Na, Mg/Y, Ga/Sr, Nd/Mg, Gd/Na or Sm/Na. In some other embodiments, the La₂O₃ or LaO_(y)(OH)_(x) nanowires are doped with a binary dopant combination, for example Ca—Mg—Na.

In other embodiments, the nanowires comprise Nd₂O₃ or NdO_(y)(OH)_(x), wherein y ranges from 0 to 1.5, x ranges from 0 to 3 and 2y+x=3, doped with Sr, Ca, Rb, Li, Na or combinations thereof. In certain other embodiments, the Nd₂O₃ or NdO_(y)(OH)_(x) nanowires are doped with binary dopant combinations, for example Ca/Sr or Rb/Sr, Ta/Sr or Al/Sr.

In still other examples of doped nanowires, the nanowires comprise Yb₂O₃ or YbO_(y)(OH)_(x), wherein y ranges from 0 to 1.5, x ranges from 0 to 3 and 2y+x=3, doped with Sr, Ca, Ba, Nd or combinations thereof. In certain other embodiments, the Yb₂O₃ or YbO_(y)(OH)_(x) OCM nanowires are doped with a binary combination, for example of Sr/Nd.

Still other examples of doped nanowires Eu₂O₃ or EuO_(y)(OH)_(x) nanowires, wherein y ranges from 0 to 1.5, x ranges from 0 to 3 and 2y+x=3, doped with Sr, Ba, Sm, Gd, Na or combinations thereof or a binary dopant combination, for example Sr/Na or Sm/Na.

Example of dopants for Sm₂O₃ or SmO_(y)(OH)_(x) nanowires, wherein x and y are each independently an integer from 1 to 10, include Sr, and examples of dopants for Y₂O₃ or YO_(y)(OH)_(x) nanowires, wherein y ranges from 0 to 1.5, x ranges from 0 to 3 and 2y+x=3, comprise Ga, La, Nd or combinations thereof. In certain other embodiments, the Y₂O₃ or YO_(y)(OH)_(x) nanowires comprise a binary dopant combination, for example Sr/Nd, Eu/Y or Mg/Nd or a tertiary dopant combination, for example Mg/Nd/Fe.

Rare earth nanowires which without doping have low OCM selectivity can be greatly improved by doping to reduce their combustion activity. In particular, nanowires comprising CeO₂ and Pr₂O₃ tend to have strong total oxidation activity for methane, however doping with additional rare earth elements can significantly moderate the combustion activity and improve the overall utility of the catalyst. Example of dopants which improving the selectivity for Pr₂O₃ or PrO_(y)(OH)_(x) nanowires, wherein y ranges from 0 to 1.5, x ranges from 0 to 3 and 2y+x=3, comprise binary dopants, for example Nd/Mg, La/Mg or Yb/Sr.

In some embodiments, dopants are present in the nanowires in, for example, less than 50 at %, less than 25 at %, less than 10 at %, less than 5 at % or less than 1 at %.

In other embodiments of the nanowires, the atomic ratio (w/w) of the one or more metal elements selected from Groups 1-7 and lanthanides and actinides in the form of an oxide and the dopant ranges from 1:1 to 10,000:1, 1:1 to 1,000:1 or 1:1 to 500:1.

In further embodiments, the nanowires comprise one or more metal elements from Group2 in the form of an oxide and a dopant from Group I. In further embodiments, the nanowires comprise magnesium and lithium. In other embodiments, the nanowires comprise one or more metal elements from Group2 and a dopant from Group 2, for example, in some embodiments, the nanowires comprise magnesium oxide and barium. In another embodiment, the nanowires comprise an element from the lanthanides in the form of an oxide and a dopant from Group 1 or Group 2. In further embodiments, the nanowires comprise lanthanum and strontium.

Various methods for preparing doped nanowires are provided. In one embodiment, the doped nanowires can be prepared by co-precipitating a nanowire metal oxide precursor and a dopant precursor. In these embodiments, the doping element may be directly incorporated into the nanowire.

Template Directed Synthesis of Nanowires

In some embodiments, the nanowires can be prepared in a solution phase using an appropriate template. In this context, an appropriate template can be any synthetic or natural material, or combination thereof, that provides nucleation sites for binding ions (e.g. metal element ions and/or hydroxide or other anions) and causing the growth of a nanowire. The templates can be selected such that certain control of the nucleation sites, in terms of their composition, quantity and location can be achieved in a statistically significant manner. The templates are typically linear or anisotropic in shape, thus directing the growth of a nanowire.

In contrast to other template directed preparation of nanowires, the present nanowires are generally not prepared from nanoparticles deposited on a template in a reduced state which are then heat treated and fused into a nanowire. Such methods are not generally applicable to nanowires comprising one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof. Instead, the nanowires are prepared by nucleation of an oxidized metal element (e.g., in the form of a metal salt) and subsequent growth of nanowire. The nanowires are then generally calcined to produce the desired oxide, but annealing of nanoparticles is not necessary to form the nanowires.

1. Biological Template

Because peptide sequences have been shown to have specific and selective binding affinity for many different types of metal element ions, biological templates incorporating peptide sequences as nucleation sites are preferred. Moreover, biological templates can be engineered to comprise pre-determined nucleation sites in pre-determined spatial relationships (e.g., separated by a few to tens of nanometers).

Both wild type and genetically engineered biological templates can be used. As discussed herein, biological templates such as proteins and bacteriophage can be engineered based on genetics to ensure control over the type of nucleation sites (e.g., by controlling the peptide sequences), their locations on the templates and their respective density and/or ratio to other nucleation sites. See, e.g., Mao, C. B. et al., (2004) Science, 303, 213-217; Belcher, A. et al., (2002) Science 296, 892-895; Belcher, A. et al., (2000) Nature 405 (6787) 665-668; Reiss et al., (2004) Nanoletters, 4 (6), 1127-1132, Flynn, C. et al., (2003) J. Mater. Sci., 13, 2414-2421; Mao, C. B. et al., (2003) PNAS, 100 (12), 6946-6951, which references are hereby incorporated by reference in their entireties. This allows for the ability to control the composition and distribution of the nucleation sites on the biological template.

Thus, biological templates may be particularly advantageous for a controlled growth of nanowires. Biological templates can be biomolecules (e.g., proteins) as well as multi-molecular structures of a biological origin, including, for example, bacteriophage, virus, amyloid fiber, and capsid.

(a) Biomolecules

In certain embodiments, the biological templates are biomolecules. In more specific embodiments, the biological templates are anisotropic biomolecules. Typically, a biomolecule comprises a plurality of subunits (building blocks) joined together in a sequence via chemical bonds. Each subunit comprises at least two reactive groups such as hydroxyl, carboxylic acid and amino groups, which enable the bond formations that interconnect the subunits. Examples of the subunits include, but are not limited to: amino acids (both natural and synthetic) and nucleotides. Accordingly, in some embodiments, the biomolecule template is a peptide, protein, nucleic acid, polynucleotide, amino acid, antibody, enzyme, or single-stranded or double-stranded nucleic acid or any modified and/or degraded forms thereof.

Because protein synthesis can be genetically directed, proteins can be readily manipulated and functionalized to contain desired peptide sequences (i.e., nucleation sites) at desired locations within the primary structure of the protein. The protein can then be assembled to provide a template.

Thus, in various embodiments, the templates are biomolecules are native proteins or proteins that can be engineered to have nucleation sites for specific ions.

(b) Baceteriophage

In one particular embodiment, the biological template comprises a M13 bacteriophage which has or can be engineered to have one or more particular peptide sequences bound onto the coat proteins. FIG. 6 schematically shows a filamentous bacteriophage 400, in which a single-stranded DNA core 410 is surrounded by a proteinaceous coat 420. The coat is composed mainly of pVIII proteins 424 that cover the length of the bacteriophage. The ends of the bacteriophage are capped by minor coat proteins 430 (pIII), 440 (pVI), 450 (pVII) and 460 (pIX).

Using genetic engineering, a library of diverse, novel peptide sequences (up to 10¹² unique peptides) can be expressed on the surface of the phage, so that each individual phage displays at least one unique peptide sequence. These externally facing peptide sequences can be tested, through the iterative steps of screening, amplification and optimization, for the ability to control nucleation and growth of specific catalytic nanowires.

For example, in a further embodiment peptide sequences having one or more particular nucleation sites specific for various ions are bound onto the coat proteins. For example, in one embodiment, the coat protein is pVIII with peptide sequences having one or more particular nucleation sites specific for various ions bound thereto. In other further embodiments, the peptide sequences bound to the coat protein comprise 2 or more amino acids, 5 or more amino acids, 10 or more amino acids, 20 or more amino acids, or 40 or more amino acids. In other embodiments, the peptide sequences bound to the coat protein comprise between 2 and 40 amino acids, between 5 and 20 amino acids, or between 7 and 12 amino acids.

One of the approaches to obtain different types of M13 bacteriophage is to modify the viral genetic code in order to change the amino acid sequence of the phage coating protein pVIII. The changes in sequence only affect the last amino acids of the pVIII protein, which are the ones that make the surface of the M13 phage, while the first 45 amino acids are left unchanged so that the packing of the pVIII proteins around the phage is not compromised. By changing the outer amino acids on the pVIII protein, the surface characteristics of the phage can be tailored to higher affinities to specific metal ions and thus promoting selective growth of specific inorganic materials on the phage surface.

(c) Amyloid Fibers

In another embodiment, amyloid fibers can be used as the biological template on which metal ions can nucleate and assemble into a catalytic nanowire. Under certain conditions, one or more normally soluble proteins (i.e., a precursor protein) may fold and assemble into a filamentous structure and become insoluble. Amyloid fibers are typically composed of aggregated I3-strands, regardless of the structure origin of the precursor protein. As used herein, the precursor protein may contain natural or unnatural amino acids. The precursor protein may be further modified with a fatty acid tail.

(d) Virus and Capsid

In further embodiments, a virus or a capsid can be used as a biological template. Similar to a bacteriophage, a virus also comprises a protein coat and a nucleic acid core. In particular, viruses of anisotropic shapes, such as viral fibers, are suitable for nucleating and growing the catalytic nanowires described herein. Further, a virus can be genetically manipulated to express specific peptides on its coat for desirable binding to the ions. Viruses that have elongated or filamentous structures include those that are described in, for example, Christopher Ring, Genetically Engineered Viruses, (Ed) Bios Scientific (2001).

In certain embodiments, the virus may have its genetic materials removed and only the exterior protein coat (capsid) remains as the biological template.

2. Nucleation

Nucleation is the process of forming an inorganic nanowire in situ by converting soluble precursors (e.g., metal salts and anions) into nanocrystals in the presence of a template (e.g., a biological template). Typically, the nucleation and growth takes place from multiple binding sites along the length of the biological template in parallel. The growth continues until a structure encasing the biological template is formed. In some embodiments this structure is single-crystalline. In other embodiments the structure is polycrystalline, and in other embodiments the structure is polycrystalline. If desired, upon completion of the synthesis the organic biological template (e.g., bacteriophage) can be removed by thermal treatment (˜300° C.) in air or oxygen, without significantly affecting either the structure or shape of the inorganic material. In addition, dopants can be either simultaneously incorporated during the growth process or, in another embodiment, dopants can be incorporated via impregnation techniques.

(a) Nanowire Growth Methods

FIG. 7 shows a flow chart of a nucleation process for forming a nanowire comprising a metal oxide. A phage solution is first prepared (block 504), to which metal salt precursor comprising metal ions is added (block 510). Thereafter, an anion precursor is added (block 520). It is noted that, in various embodiments, the additions of the metal ions and anion precursor can be simultaneous or sequentially in any order. Under appropriate conditions (e.g., pH, molar ratio of the phage and metal salt, molar ratio of the metal ions and anions, addition rate, etc.), the metal ions and anions become bound to the phage, nucleate and grow into a nanowire of M_(m)X_(n)Z_(p) composition (block 524). Following calcinations, nanowires comprising M_(m)X_(n) are transformed to nanowires comprising metal oxide (M_(x)O_(y)) (block 530). An optional step of doping (block 534) incorporates a dopant (D^(p+)) in the nanowires comprising metal oxide (M_(x)O_(y), wherein x and y are each independently a number from 1 to 100.

Thus, one embodiment provides a method for preparing a metal oxide nanowire comprising a plurality of metal oxides (M_(x)O_(y)), the method comprising:

a) providing a solution comprising a plurality of biological templates;

(b) introducing at least one metal ion and at least one anion to the solution under conditions and for a time sufficient to allow for nucleation and growth of a nanowire comprising a plurality of metal salts (M_(m)X_(n)Z_(p)) on the template; and

(c) converting the nanowire (M_(m)X_(n)Z_(p)) to a metal oxide nanowire comprising a plurality of metal oxides (M_(x)O_(y)),

wherein:

M is, at each occurrence, independently a metal element from any of Groups 1 through 7, lanthanides or actinides;

X is, at each occurrence, independently hydroxides, carbonates, bicarbonates, phosphates, hydrogenphosphates, dihydrogenphosphates, sulfates, nitrates or oxalates;

Z is O;

n, m, x and y are each independently a number from 1 to 100; and

p is a number from 0 to 100.

In certain variations of the foregoing, two or more different metal ions may be used. This produces nanowires comprising a mixture of two or more metal oxides. Such nanowires may be advantageous in certain catalytic reactions. For example, in some embodiments a nanowire may comprise two or more different metal oxides where at least one of the metal oxides has good OCM activity and at least one metal oxide has good ODH activity.

In certain embodiments of the above, Applicants have found that it may be advantageous to perform multiple sequential additions of the metal ion, This addition technique may be particularily applicable to embodiments wherein two or more different metal ions oare employed to form a mixed nanowire (M1 M2X_(x)Y_(y), wherein M1 and M2 are different metal elements), which can be converted to M1 M2O_(z), for example by calcination. The slow addition may be performed over any period of time, for example from 1 day to 1 week. In this regard, use of a syringe pump may be advantageous. Slow addition of the components help ensure that they will nucleate on the biological template instead of non-selectively precipitate.

In various embodiments, the biological templates are phages, as defined herein. In further embodiments, the metal ion is provided by adding one or more metal salt (as described herein) to the solution. In other embodiments, the anion is provided by adding one or more anion precursor to the solution. In various embodiments, the metal ion and the anion can be introduced to the solution simultaneously or sequentially in any order. In some embodiments, the nanowire (M_(m)X_(n)Z_(p)) is converted to a metal oxide nanowire by calcination, which is a thermal treatment that transforms or decomposes the M_(m)X_(n)Z_(p) nanowire to a metal oxide. In yet another embodiment, the method further comprises doping the metal oxide nanowire with a dopant. Converting the nanowire to a metal oxide generally comprises calcining.

In a variation of the above method, mixed metal oxides can be prepared (as opposed to a mixture of metal oxides). Mixed metal oxides can be represented by the following formula M1_(w)M2_(x)M3_(y)O_(z), wherein M1, M2 and M3 are each independently absent or a metal element, and w, x, y and z are integers such that the overall charge is balanced. Mixed metal oxides comprising more than three metals are also contemplated and can be prepared via an analogous method. Such mixed metal oxides find utility in a variety of the catalytic reactions disclosed herein. One exemplary mixed metal oxide is Na₁₀MnW₅O₁₇ (Example 18).

Thus, one embodiment provides a method for preparing a mixed metal oxide nanowire comprising a plurality of mixed metal oxides (M1_(w)M2_(x)M3_(y)O_(z)), the method comprising:

a) providing a solution comprising a plurality of biological templates;

(b) introducing metal salts comprising M1, M2 and M3 to the solution under conditions and for a time sufficient to allow for nucleation and growth of a nanowire comprising a plurality of the metal salts on the template; and

(c) converting the nanowire to a mixed metal oxide nanowire comprising a plurality of mixed metal oxides (M1_(w)M2_(x)M3_(y)O_(z)),

wherein:

M1, M2 and M3 are, at each occurrence, independently a metal element from any of Groups 1 through 7, lanthanides or actinides;

n, m, x and y are each independently a number from 1 to 100; and

p is a number from 0 to 100.

In other embodiments, the present disclosure provides a method for preparing metal oxide nanowires which may not require a calcination step. Thus, in some embodiments the method for preparing metal oxide nanowires comprises:

(a) providing a solution that includes a plurality of biological templates; and

(b) introducing a compound comprising a metal to the solution under conditions and for a time sufficient to allow for nucleation and growth of a nanowire (M_(m)Y_(n)) on the template;

wherein:

M is a metal element from any of Groups 1 through 7, lanthanides or actinides;

Y is O;

n and m are each independently a number from 1 to 100.

In some specific embodiments of the foregoing method, M is an early transition metal, for example V, Nb, Ta, Ti, Zr, Hf, W, Mo or Cr. In other embodiments, the metal oxide is W03. In yet another embodiment, the method further comprises doping the metal oxide nanowire with a dopant. In some further embodiments, a reagent is added which converts the compound comprising a metal into a metal oxide.

In another embodiment, nanowires are prepared by using metal salts sensitive to water hydrolysis, for example NbCl₅, WCl₆, TiCl₄, ZrCl₄. A template can be placed in ethanol along with the metal salt. Water is then slowly added to the reaction in order to convert the metals salts to metal oxide coated template.

By varying the nucleation conditions, including (without limitation): incubation time of phage and metal salt; incubation time of phage and anion; concentration of phage; metal ion concentration, anion concentration, sequence of adding anion and metal ions; pH; phage sequences; solution temperature in the incubation step and/or growth step; types of metal precursor salt; types of anion precursor; addition rate; number of additions; amount of metal salt and/or anion precursor per addition, the time that lapses between the additions of the metal salt and anion precursor, including, e.g., simultaneous (zero lapse) or sequential additions followed by respective incubation times for the metal salt and the anion precursor, stable nanowires of diverse compositions and surface properties can be prepared. For example, in certain embodiments the pH of the nucleation conditions is at least 7.0, at least 8.0, at least 9.0, at least 10.0, at least 11.0, at least 12.0 or at least 13.0.

As noted above, the rate of addition of reactants (e.g., metal salt, metal oxide, anion precursor, etc.) is one parameter that can be controlled and varied to produce nanowires having different properties. During the addition of reactants to a solution containing an existing nanowire and/or a templating material (e.g., phage), a critical concentration is reached for which the speed of deposition of solids on the existing nanowire and/or templating material matches the rate of addition of reactants to the reaction mixture. At this point, the concentration of soluble cation stabilizes and stops rising. Thus, nanowire growth can be controlled and maximized by maintaining the speed of addition of reactants such that near super-saturation concentration of the cation is maintained. This helps ensure that no undesirable nucleation occurs. If super-saturation of the anion (e.g., hydroxide) is exceeded, a new solid phase can start nucleating which allows for non-selective solid precipitation, rather than nanowire growth. Thus, in order to selectively deposit an inorganic layer on an existing nanowire and/or a templating material, the addition rate of reactants should be controlled to avoid reaching super-saturation of the solution containing the suspended solids.

Accordingly, in one embodiment, reactant is repeatedly added in small doses to slowly build up the concentration of the reactant in the solution containing the template. In some embodiments, the speed of addition of reactant is such that the reactant concentration in the solution containing the template is near (but less than) the saturation point of the reactant. In some other embodiments, the reactant is added portion wise (i.e., step addition) rather than continuously. In these embodiments, the amount of reactant in each portion, and the time between addition of each portion, is controlled such that the reactant concentration in the solution containing the template is near (but less than) the saturation point of the reactant. In certain embodiments of the foregoing, the reactant is a metal cation while in other embodiments the reactant is an anion.

Initial formation of nuclei on a template can be obtained by the same method described above, wherein the concentration of reactant is increased until near, but not above, the supersaturation point of the reactant. Such an addition method facilitates nucleation of the solid phase on the template, rather than homogeneous non-seeding nucleation. In some embodiments, it is desirable to use a slower reactant addition speed during the initial nucleation phase as the super-saturation depression due to the template might be quite small at this point. Once the first layer of solid (i.e., nanowire) is formed on the template, the addition speed can be increased.

In some embodiments, the addition rate of reactant is controlled such that the precipitation rate matches the addition rate of the reactant. In these embodiments, nanowires comprising two or more different metals can be prepared by controlling the addition rates of two or more different metal cation solutions such that the concentration of each cation in the templating solution is maintained at or near (but does not exceed) the saturation point for each cation.

In some embodiments, the optimal speed of addition (and step size if using step additions) is controlled as a function of temperature. For example, in some embodiments the nanowire growth rate is accelerated at higher temperatures. Thus, the addition rate of reactants is adjusted according to the temperature of the templating solution.

In other embodiments, modeling (iterative numeric rather than algebraic) of the nanowire growth process is used to determine optimal solution concentrations and supernatant re-cycling strategies.

As noted above, the addition rate of reactants can be controlled and modified to change the properties of the nanowires. In some embodiments, the addition rate of a hydroxide source must be controlled such that the pH of the templating solution is maintained at the desired level. This method may require specialized equipment, and depending on the addition rate, the potential for localized spikes in pH upon addition of the hydroxide source is possible. Thus, in an alternative embodiment the present disclosure provides a method wherein the template solution comprises a weak base that slowly generates hydroxide in-situ, obviating the need for an automated addition sequence.

In the above embodiment, organic epoxides, such as but not limited to propylene oxide and epichlorohydrin, are used to slowly increase the template solution pH without the need for automated pH control. The epoxides are proton scavengers and undergo an irreversible ring-opening reaction with a nucleophilic anion of the metal oxide precursor (such as but not limited to Cl⁻ or NO₃ ⁻). The net effect is a slow homogenous raise in pH to form metal hydroxy species in solution that deposit onto the template surface. In some embodiments, the organic epoxide is propylene oxide.

An attractive feature of this method is that the organic epoxide can be added all at once, there is no requirement for subsequent additions of organic epoxide to grow metal oxide coatings over the course of the reaction. Due to the flexibility of the “epoxide-assisted” coatings, it is anticipated that many various embodiments can be employed to make new templated materials (e.g., nanowires). For example, mixed metal oxide nanowires can be prepared by starting with appropriate ratios of metal oxide precursors and propylene oxide in the presence of bacteriophage. In other embodiments, metal oxide deposition on bacteriophage can be done sequentially to prepare core/shell materials (described in more detail below).

(b) Metal Salt

As noted above, the nanowires are prepared by nucleation of metal ions in the presence of an appropriate template, for example, a bacteriophage. In this respect, any soluble metal salt may be used as the precursor of metal ions that nucleate on the template. Soluble metal salts of the metals from Groups 1 through 7, lanthanides and actinides are particularly useful and all such salts are contemplated.

In one embodiment, the soluble metal salt comprises chlorides, bromides, iodides, nitrates, sulfates, acetates, oxides, oxyhalides, oxynitrates, phosphates (including hydrogenphosphate and dihydrogenphosphate) or oxalates of metal elements from Groups 1 through 7, lanthanides, actinides or combinations thereof. In more specific embodiments, the soluble metal salt comprises chlorides, nitrates or sulfates of metal elements from Groups 1 through 7, lanthanides, actinides or combinations thereof. The present disclosure contemplates all possible chloride, bromide, iodide, nitrate, sulfate, acetate, oxide, oxyhalides, oxynitrates, phosphates (including hydrogenphosphate and dihydrogenphosphate) and oxalate salts of metal elements from Groups 1 through 7, lanthanides, actinides or combinations thereof. In another embodiment, the metal salt comprises LiCl, LiBr, Lil, LiNO₃, Li₂SO₄, LiCO₂CH₃, Li₂C₂O₄, NaCl, NaBr, NaI, NaNO₃, Na₂SO₄, NaCO₂CH₃, Na₂C₂O₄, KCI, KBr, KI, KNO₃, K₂SO₄, KCO₂CH₃, K₂C₂O₄, RbCl, RbBr, RbI, RbNO₃, Rb₂SO₄, RbCO₂CH₃, Rb₂C₂O₄, CsCl, CsBr, CsI, CsNO₃, Cs₂SO₄, CsCO₂CH₃, Cs₂C₂O₄, BeCl₂, BeBr₂, BeI₂, Be(NO₃)₂, BeSO₄, Be(CO₂CH₃)₂, BeC₂O₄, MgCl₂, MgBr₂, MgI₂, Mg(NO₃)₂, MgSO₄, Mg(CO₂CH₃)₂, MgC₂O₄, CaCl₂, CaBr₂, CaI₂, Ca(NO₃)₂, CaSO₄, Ca(CO₂CH₃)₂, CaC₂O₄, SrCl₂, SrBr₂, SrI₂, Sr(NO₃)₂, SrSO₄, Sr(CO₂CH₃)₂, SrC₂O₄, BaCl₂, BaBr₂, BaI₂, Ba(NO₃)₂, BaSO₄, Ba(CO₂CH₃)₂, BaC₂O₄, ScCl₃, ScBr₃, ScI₃, Sc(NO₃)₃, Sc₂(SO₄)₃, Sc(CO₂CH₃)₃, Sc₂(C₂O₄)₃,YCl₃, YBr₃, YI₃, Y(NO₃)₃, Y₂(SO₄)₃, Y(CO₂CH₃)₃, Y₂(C₂O₄)₃,TiCl₄, TiBr₄, TiI₄, Ti(NO₃)₄, Ti(SO₄)₂, Ti(CO₂CH₃)₄, Ti(C₂O₄)₂, ZrCl₄, ZrOCl₂, ZrBr₄, ZrI₄, Zr(NO₃)₄, ZrO(NO₃)₂, Zr(SO₄)₂, Zr(CO₂CH₃)₄, Zr(C₂O₄)₂, HfCl₄, HfBr₄, Hfl₄, Hf(NO₃)₄, Hf(SO₄)₂, Hf(CO₂CH₃)₄, Hf(C₂O₄)₂, LaCl₃, LaBr₃, LaI₃, La(NO₃)₃, La₂(SO₄)₃, La(CO₂CH₃)₃, La₂(C₂O₄)₃, WCl₂, WCl₃, WCl₄, WCl₅, WCl₆, WBr₂, WBr₃, WBr₄, WBr₅, WBr₆, WI₂, WI₃, WI₄, WI₅, WI₆, W(NO₃)₂, W(NO₃)₃, W(NO₃)₄, W(NO₃)₅, W(NO₃)₆, W(CO₂CH₃)₂, W(CO₂CH₃)₃, W(CO₂CH₃)₄, W(CO₂CH₃)₅, W(CO₂CH₃)₆, WC₂O₄, W₂(C₂O₄)₃, W(C₂O₄)₂, W₂(C₂O₄)₅, W(C₂O₄)₆, MoCl₄, MnCl₂ MnCl₃, MnBr₂ MnBr₃, MnI₂ MnI₃, Mn(NO₃)₂, Mn(NO₃)₃, MnSO₄, Mn₂(SO₄)₃, Mn(CO₂CH₃)₂, Mn(CO₂CH₃)₃, MnC₂O₄, Mn₂(C₂O₄)₃, MoCl₂, MoCl₃, MoCl₄, MoCl₅, MoBr₂, MoBr₃, MoBr₄, MoBr₅, MoI₂, MoI₃, MoI₄, MoI₅, Mo(NO₃)₂, Mo(NO₃)₃, Mo(NO₃)₄, Mo(NO₃)₅, MoSO₄, Mo₂(SO₄)₃, Mo(SO₄)₂, Mo₂(SO₄)₅, Mo(CO₂CH₃)₂, Mo(CO₂CH₃)₃, Mo(CO₂CH₃)₄, Mo(CO₂CH₃)₅, MoC₂O₄, Mo₂(C₂O₄)₃, Mo(C₂O₄)₂, Mo₂(C₂O₄)₅, VCl, VCl₂, VCl₃, VCl₄, VBr, VBr₂, VBr₃, VBr₄, VI, VI₂, VI₃, VI₄, VNO₃, V(NO₃)₂, V(NO₃)₃, V(NO₃)₄, V₂SO₄, VSO₄, V₂(SO₄)₃, V(SO₄)₄, VCO₂CH₃, V(CO₂CH₃)₂, V(CO₂CH₃)₃, V(CO₂CH₃)₄, V₂C₂O₄, VC₂O₄, V₂(C₂O₄)₃,V(C₂O₄)₄, NdCl₃, NdBr₃, NdI₃, Nd(NO₃)₃, Nd₂(SO₄)₃, Nd(CO₂CH₃)₃, Nd₂(C₂O₄)₃,EUCl₃, EUBr₃, EUI₃, EU(NO₃)₃, EU₂(SO₄)₃, EU(CO₂CH₃)₃, EU₂(C₂O₄)₃, PrCl₃, PrBr₃, PrI₃, Pr(NO₃)₃, Pr₂(SO₄)₃, Pr(CO₂CH₃)₃, Pr₂(C₂O₄)₃, SmCl₃, SmBr₃, SmI₃, SM(NO₃)₃, Sm₂(SO₄)₃, Sm(CO₂CH₃)₃, SM₂(C₂O₄)₃, CeCl₃, CeBr₃, CeI₃, Ce(NO₃)₃, Ce₂(SO₄)₃, Ce(CO₂CH₃)₃, Ce₂(C₂O₄)₃ or combinations thereof.

In more specific embodiments, the metal salt comprises MgCl₂, LaCl₃, ZrCl₄, WCl₄, MoCl₄, MnCl₂ MnCl₃, Mg(NO₃)₂, La(NO₃)₃, ZrOCl₂, Mn(NO₃)₂, Mn(NO₃)₃, ZrO(NO₃)₂, Zr(NO₃)₄, or combinations thereof.

In other embodiments, the metal salt comprises NdCl₃, NdBr₃, NdI₃, Nd(NO₃)₃, Nd₂(SO₄)₃, Nd(CO₂CH₃)₃, Nd₂(C₂O₄)₃,EuCl₃, EuBr₃, EuI₃, EU(NO₃)₃, EU₂(SO₄)₃, EU(CO₂CH₃)₃, EU₂(C₂O₄)₃, PrCl₃, PrBr₃, PrI₃, Pr(NO₃)₃, Pr₂(SO₄)₃, Pr(CO₂CH₃)₃, Pr₂(C₂O₄)₃ or combinations thereof.

In still other embodiments, the metal salt comprises Mg, Ca, Mg, W, La, Nd, Sm, Eu, W, Mn, Zr or mixtures thereof. The salt may be in the form of (oxy)chlorides, (oxy)nitrates or tungstates.

(c) Anion Precursor

The anions, or counter ions of the metal ions that nucleate on the template, are provided in the form of an anion precursor. The anion precursor dissociates in the solution phase and releases an anion. Thus, the anion precursor can be any stable soluble salts having the desired anion. For instance, bases such as alkali metal hydroxides (e.g., sodium hydroxide, lithium hydroxide, potassium hydroxides) and ammonium hydroxide are anion precursors that provide hydroxide ions for nucleation. Alkali metal carbonates (e.g., sodium carbonate, potassium carbonates) and ammonium carbonate are anion precursors that provide carbonates ions for nucleation.

In certain embodiments, the anion precursor comprises one or more metal hydroxide, metal carbonate, metal bicarbonate, or metal oxalate. Preferably, the metal is an alkali or an alkaline earth metal. Thus, the anion precursor may comprise any one of alkali metal hydroxides, carbonates, bicarbonates, or oxalate; or any one of alkaline earth metal hydroxide, carbonates, bicarbonates, or oxalate.

In some specific embodiments, the one or more anion precursors comprises LiOH, NaOH, KOH, Sr(OH)₂, Ba(OH)₂, Na₂CO₃, K₂CO₃, NaHCO₃, KHCO₃, and NR₄OH, wherein R is selected from H, and C₁-C₆ alkyl. Ammonium salts may provide certain advantages in that there is less possibility of introducing unwanted metal impurities. Accordingly, in a further embodiment, the anion precursor comprises ammonium hydroxide.

The dimensions of the nanowires are comparable to those of the biological templates (e.g., phage), although they can have different aspect ratios as longer growth can be used to increase the diameter while the length will increase in size at a much slower rate. The spacing of peptides on the phage surface controls the nucleation location and the catalytic nanowire size based on steric hindrance. The specific peptide sequence information can (or may) dictate the identity, size, shape and crystalline face of the catalytic nanowire being nucleated. To achieve the desired stochiometry between metal elements, support and dopants, multiple peptides specific for these discrete materials can be co-expressed within the same phage. Alternatively, precursor salts for the materials can be combined in the reaction at the desired stochiometry. The techniques for phage propagation and purification are also well established, robust and scalable. Multi-kilogram amounts of phage can be easily produced, thus assuring straightforward scale up to large, industrial quantities.

Typical functional groups in amino acids that can be used to tailor the phage surface affinity to metal ions include: carboxylic acid (—COOH), amino (—NH₃ ⁺ or —NH₂), hydroxyl (—OH), and/or thiol (—SH) functional groups. Table 9 summarizes a number of exemplary phages used in the present invention for preparing nanowires of inorganic metal oxides. Sequences within Table 9 refer to the amino acid sequence of the pVIII protein (single-letter amino acid code). Underlined portions indicate the terminal sequence which was varied to tailor the phage surface affinity to metal ions. SEQ ID NO 14 represents wild type pVIII protein while SEQ ID NO 15 represents wild type pVIII protein including the signaling peptide portion (bold).

TABLE 9 SEQ ID NO Sequence  1 AEEGSEDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS  2 EEGSDDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS  3 AEEEDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS  4 EEEDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS  5 AEEEEDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS  6 AEEAEDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS  7 EEXEDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS X = E or G  8 AEDDDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS  9 AVSGSSPGDDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS 10 AVSGSSPDSDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS 11 AGETQQAMEDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS 12 AAGETQQAMDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS 13 AEPGHDAVPEDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS 14 AEGDDDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS 15 MKKSLVLKASVAVATLVPMLSFA AEGDDDPAKAAFNSLQASATEYIGYAWAMVVVIVGATIGIKLFKKFTSKAS

3. Core/Shell Structures

In certain embodiments, nanowires can be grown on a support nanowire that has no or a different catalytic property. FIG. 8 shows an exemplary process 600 for growing a core/shell structure. Similar to FIG. 7, a phage solution is prepared (block 604), to which a first metal salt and a first anion precursor are sequentially added (blocks 610 and 620) in appropriate conditions to allow for the nucleation and growth of a nanowire (M1_(m1)X1_(n1)Z_(p1)) on the phage (block 624). Thereafter, a second metal salt and a second anion precursor are sequentially added (blocks 630 and 634), under conditions to cause the nucleation and growth of a coating of M2_(m2)X2_(n2)Z_(p2) on the nanowire M1_(m1)X1_(n1)Z_(p1) (block 640). Following calcinations, nanowires of a core/shell structure M1_(x1)O_(y1)/M2_(x2)O_(y2) are formed, wherein x1, y1, x2 and y2 are each independently a number from 1 to 100, and p1 and p2 are each independently a number from 0 to 100 (block 644). A further step of impregnation (block 650) produces a nanowire comprising a dopant and comprising a core of M1_(x1)O_(y1) coated with a shell of M2_(x2)O_(y2). In some embodiments, M1 is Mg, Al, Ga, Ca or Zr. In certain embodiments of the foregoing, M1 is Mn and M2 is Mg. In other embodiments, M1 is Mg and M2 is Mn. In other embodiments, M1 is La and M2 is Mg, Ca, Sr, Ba, Zr, Nd, Y, Yb, Eu, Sm or Ce. In other embodiments, M1 is Mg and M2 is La or Nd.

In other embodiments, M1_(x1)O_(y1) comprises La₂O₃ while in other embodiments M2_(x2)O_(y2) comprises La₂O₃. In other embodiments of the foregoing, M1_(x1)O_(y)i or M2_(x2)O_(y)2 further comprises a dopant, wherein the dopant comprises Nd, Mn, Fe, Zr, Sr, Ba, Y or combinations thereof. Other specific combinations of core/shell nanowires are also envisioned within the scope of the present disclosure.

Thus, one embodiment provides a method for preparing metal oxide nanowires in a core/shell structure, the method comprising:

(a) providing a solution that includes a plurality of biological templates;

(b) introducing a first metal ion and a first anion to the solution under conditions and for a time sufficient to allow for nucleation and growth of a first nanowire (M1_(m1)X1_(n1)Z_(p1)) on the template; and

(c) introducing a second metal ion and optionally a second anion to the solution under conditions and for a time sufficient to allow for nucleation and growth of a second nanowire (M2_(m2)X2_(n2)Z_(p2)) on the first nanowire (M1_(m1)X1_(n1)Z_(p1)),

(d) converting the first nanowire (M1_(m1)X1_(n1)Z_(p1)) and the second nanowire (M2_(m2)X2_(n2)Z_(p2)) to respective metal oxide nanowires (M1_(x1)O_(y1)) and (M2_(x2)O_(y2)),

wherein:

M1 and M2 are the same or different and independently selected from a metal element;

X1 and X2 are the same or different and independently hydroxides, carbonates, bicarbonates, phosphates, hydrogenphosphates, dihydrogenphosphates, sulfates, nitrates or oxalates;

Z is O;

n1, m1, m1, m2, x1, y1, x2 and y2 are each independently a number from 1 to 100; and

p1 and p2 are independently a number from 0 to 100.

In some embodiments, M1 and M2 are the same or different and independently selected from a metal element from any of Groups 2 through 7, lanthanides or actinides

In various embodiments, the biological templates are phages, as defined herein. In further embodiments, the respective metal ion is provided by adding one or more respective metal salts (as described herein) to the solution. In other embodiments, the respective anions are provided by adding one or more respective anion precursors to the solution. In various embodiments, the first metal ion and the first anion can be introduced to the solution simultaneously or sequentially in any order. Similarly, the second metal ion and optionally the second anion can be introduced to the solution simultaneously or sequentially in any order. The first and second nanowire are typically converted to a metal oxide nanowire in a core/shell structure by calcination.

In yet another embodiment, the method further comprises doping the metal oxide nanowire in a core/shell structure with a dopant.

By varying the nucleation conditions, including the pH of the solution, relative ratio of metal salt precursors and the anion precursors, relative ratios of the precursors and the phage of the synthetic mixture, stable nanowires of diverse compositions and surface properties can be prepared.

In certain embodiments, the core nanowire (the first nanowire) is not catalytically active or less so than the shell nanowire (the second nanowire), and the core nanowire serve as an intrinsic catalytic support for the more active shell nanowire. For example, ZrO₂ may nt have high catalytic activity in an OCM reaction, whereas Sr²⁺ doped La₂O₃ does. A ZrO₂ core thus may serve as a support for the catalytic Sr²⁺ doped La₂O₃ shell.

In some embodiments, the present disclosure provides a nanowire comprising a core/shell structure and comprising a ratio of effective length to actual length of less than one. In other embodiments, the nanowires having a core/shell structure comprise a ratio of effective length to actual length equal to one.

Nanowires in a core/shell arrangement may be prepared in the absence of a biological template. For example, a nanowire comprising a first metal may be prepared according to any of the non-template directed methods described herein. A second metal may then be nucleated or plated onto the nanowire to form a core/shell nanowire. The first and second metals may be the same or different. Other methods for preparing core/shell nanowires in the absence of a biological template are also envisaged.

4. Diversity

As noted above, in some embodiments, the disclosed template-directed synthesis provides nanowires having diverse compositions and/or morphologies. This method combines two extremely powerful approaches, evolutionary selection and inorganic synthesis, to produce a library of nanowire catalysts with a new level of control over materials composition, materials surface and crystal structure. These nanowires prepared by biologically-templated methods take advantage of genetic engineering techniques to enable combinatorial synthesis of robust, active and selective inorganic catalytic polycrystalline nanowires. With selection, evolution and a combinatorial library with over a hundred billion sequence possibilities, nanowires having high specificity and product conversion yields in catalytic reactions are generated. This permits simultaneous optimization the nanowires' catalytic properties in a high-dimensional space.

In various embodiments, the synthetic parameters for nucleating and growing nanowires can be manipulated to create nanowires of diverse compositions and morphologies. Typical synthetic parameters include, without limitation, concentration ratios of metal ions and active functional groups on the phage; concentration ratios of metal and anions (e.g., hydroxide); incubation time of phage and metal salt; incubation time of phage and anion; concentration of phage; sequence of adding anion and metal ions; pH; phage sequences; solution temperature in the incubation step and/or growth step; types of metal precursor salt; types of anion precursor; addition rate, number of additions; the time that lapses between the additions of the metal salt and anion precursor, including, e.g., simultaneous (zero lapse) or sequential additions followed by respective incubation times for the metal salt and the anion precursor.

Additional variable synthetic parameters include, growth time once both metal and anion are present in the solution; choice of solvents (although water is typically used, certain amounts of alcohol, such as methanol, ethanol and propanol, can be mixed with water); choice and the number of metal salts used (e.g., both LaCl₃ and La(NO₃)₃ can be used to provide La³⁺ ions); choice and the number of anion precursors used (e.g., both NaOH then LiOH can be used to provide the hydroxide); choice or the number of different phage sequences used; the presence or absence of a buffer solution; the different stages of the growing (e.g., nanowires may be precipitated and cleaned and resuspended in a second solution and perform a second growth of the same material (thicker core) or different material to form a core/shell structure.

Thus, libraries of nanowires can be generated with diverse physical properties and characteristics such as: composition, e.g., basic metal oxides (M_(x)O_(y)), size, shape, surface morphology, exposed crystal faces/edge density, crystallinity, dispersion, and stoichiometry and nanowire template physical characteristics including length, width, porosity and pore density. High throughput, combinatorial screening methods are then applied to evaluate the catalytic performance characteristics of the nanowires (see, e.g., FIG. 2). Based on these results, lead target candidates are identified. From these lead targets, further rational modifications to the synthetic designs can be made to create nanowires that satisfy certain catalytic performance criteria. This results in further refinement of the nanowire design and material structure.

Direct Synthesis of Nanowires

In some embodiments, the nanowires can be synthesized in a solution phase in the absence of a template. Typically, a hydrothermal or sol gel approach can be used to create straight (i.e., ratio of effective length to actual length equal to one) and substantially single crystalline nanowires. As an example, nanowires comprising a metal oxide can be prepared by (1) forming nanowires of a metal oxide precursor (e.g., metal hydroxide) in a solution of a metal salt and an anion precursor; (2) isolating the nanowires of the metal oxide precursor; and (3) calcining the nanowires of the metal oxide precursor to provide nanowires of a corresponding metal oxide. In other embodiments (for example MgO nanowires), the synthesis goes through an intermediate which can be prepared as a nanowire and then converted into the desired product while maintaining its morphology. Optionally, the nanowires comprising a metal oxide can be doped according to methods described herein.

In other certain embodiment, nanowires comprising a core/shell structure are prepared in the absence of a biological template. Such methods may include, for example, preparing a nanowire comprising a first metal and growing a shell on the outersurface of this nanowire, wherein the shell comprises a second metal. The first and second metals may be the same or different.

In other aspects, a core/shell nanowire is prepared in the absence of a biological template. Such methods comprise preparing a nanowire comprising an inner core and an outer shell, wherein the inner core comprises a first metal, and the outer shell comprises a second metal, the method comprising:

-   -   a) preparing a first nanowire comprising the first metal; and     -   b) treating the first nanowire with a salt comprising the second         metal.

In some embodiments of the foregoing method, the method further comprises addition of a base to a solution obtained in step b). In yet other examples, the first metal and the second metal are different. In yet further embodiments, the salt comprising the second metal is a halide or a nitrate. In certain aspects it may be advantageous to perform one or more sequential additions of the salt comprising the second metal and a base. Such sequential additions help prevent non-selective precipitation of the second metal and favor conditions wherein the second metal nucleates on the surface of the first nanowire to form a shell of the second metal. Furthermore, the first nanowire may be prepared by any method, for example via a template directed method (e.g., phage).

As in the template-directed synthesis, the synthetic conditions and parameters of the direct synthesis of nanowires can also be adjusted to create diverse compositions and surface morphologies (e.g., crystal faces) and dopant levels. For example, variable synthetic parameters include: concentration ratios of metal and anions (e.g., hydroxide); reaction temperature; reaction time; sequence of adding anion and metal ions; pH; types of metal precursor salt; types of anion precursor; number of additions; the time that lapses between the additions of the metal salt and anion precursor, including, e.g., simultaneous (zero lapse) or sequential additions followed by respective incubation times for the metal salt and the anion precursor.

In addition, the choice of solvents or surfactants may influence the crystal growth of the nanowires, thereby generating different nanowire dimensions (including aspect ratios). For example, solvents such as ethylene glycol, poly(ethylene glycol), polypropylene glycol and poly(vinyl pyrrolidone) can serve to passivate the surface of the growing nanowires and facilitate a linear growth of the nanowire.

In some embodiments, nanowires can be prepared directly from the corresponding oxide. For example, metal oxides may be treated with halides, for example ammonium halides, to produce nanowires. Such embodiments find particular utility in the context of lanthanide oxides, for example La₂O₃, are particularly useful since the procedure is quite simple and economically efficient Nanowires comprising two or more metals and/or dopants may also be prepared according to these methods. Accordingly, in some embodiments at least one of the metal compounds is an oxide of a lanthanide element. Such methods are described in more detail in the examples.

Accordingly, in one embodiment the present disclosure provides a method for preparing a nanowire in the absence of a biological template, the method comprising treating at least one metal compound with a halide. In certain embodiments, nanowires comprising more than one type of metal and/or one or more dopants can be prepared by such methods. For example, in one embodiment the method comprises treating two or more different metal compounds with a halide and the nanowire comprises two or more different metals. The nanowire may comprise a mixed metal oxide, metal oxyhalide, metal oxynitrate or metal sulfate.

In some other embodiments of the foregoing, the halide is in the form of an ammonium halide. In yet other embodiments, the halide is contacted with the metal compound in solution or in the solid state.

In certain embodiments, the method is useful for incorporation of one or more doping elements into a nanowire. For example, the method may comprise treating at least one metal compound with a halide in the presence of at least one doping element, and the nanowire comprises the least one doping element. In some aspects, the at least one doping element is present in the nanowire in an atomic percent ranging from 0.1 to 50 at %.

Other methods for preparation of nanowires in the absence of a biological template include preparing a hydroxide gel by reaction of at least one metal salt and a hydroxide base. For example, the method may further comprise aging the gel, heating the gel or combinations thereof. In certain other embodiments, the method comprises reaction of two or more different metal salts, and the nanowire comprises two or more different metals.

Doping elements may also be incorporated by using the hydroxide gel method described above, further comprising addition of at least one doping element to the hydroxide gel, and wherein the nanowire comprises the at least one doping element. For example, the at least one doping element may be present in the nanowire in an atomic percent ranging from 0.1 to 50 at %.

In some embodiments, metal oxide nanowires can be prepared by mixing a metal salt solution and an anion precursor so that a gel of a metal oxide precursor is formed. This method can work for cases where the typical morphology of the metal oxide precursor is a nanowire. The gel is thermally treated so that crystalline nanowires of the metal oxide precursor are formed. The metal oxide precursor nanowires are converted to metal oxide nanowires by calcination. This method can be especially useful for lanthanides and group 3 elements. In some embodiments, the thermal treatment of the gel is hydrothermal (or solvothermal) at temperatures above the boiling point of the reaction mixture and at pressures above ambient pressure, in other embodiments it's done at ambient pressure and at temperatures equal to or below the boiling point of the reaction mixture. In some embodiments the thermal treatment is done under reflux conditions at temperatures equal to the boiling point of the mixture. In some specific embodiments the anion precursor is a hydroxide, e.g. Ammonium hydroxide, sodium hydroxide, lithium hydroxide, tetramethyl ammonium hydroxide, and the like. In some other specific embodiments the metal salt is LnCl₃ (Ln=Lanthanide), in other embodiment the metal salt is Ln(NO₃)₃. In yet other embodiments, the metal salt is YCl₃, ScCl₃, Y(NO₃)₃, Sc(NO₃)₃. In some other embodiments, the metal precursor solution is an aqueous solution. In other embodiments, the thermal treatment is done at T=100° C. under reflux conditions.

This method can be used to make mixed metal oxide nanowires, by mixing at least two metal salt solutions and an anion precursor so that a mixed oxide precursor gel is formed. In such cases, the first metal may be a lathanide or a group 3 element, and the other metals can be from other groups, including groups 1-14.

In some different embodiments, metal oxide nanowires can be prepared in a similar way as described above by mixing a metal salt solution and an anion precursor so that a gel of a metal hydroxide precursor is formed. This method works for cases where the typical morphology of the metal hydroxide precursor is a nanowire. The gel is treated so that crystalline nanowires of the metal hydroxide precursor are formed. The metal hydroxide precursor nanowires are converted to metal hydroxide nanowires by base treatment and finally converted to metal oxide nanowires by calcination. This method may be especially applicable for group 2 elements, for example Mg. In some specific embodiments, the gel treatment is a thermal treatment at temperatures in the range 50-100° C. followed by hydrothermal treatment. In other embodiments, the gel treatment is an aging step. In some embodiments, the aging step takes at least one day. In some specific embodiments, the metal salt solution is a concentrated metal chloride aqueous solution and the anion precursor is the metal oxide. In some more specific embodiments, the metal is Mg. In certain embodiments of the above, these methods can be used to make mixed metal oxide nanowires. In these embodiments, the first metal is Mg and the other metal can be any other metal of groups 1-14 +Ln.

Catalytic Reactions

The present disclosure provides for the use of catalytic nanowires as catalysts in catalytic reactions and related methods. The morphology and composition of the catalytic nanowires is not limited, and the nanowires may be prepared by any method. For example the nanowires may have a bent morphology or a straight morphology and may have any molecular composition. In some embodiments, the nanowires have better catalytic properties than a corresponding bulk catalyst (i.e., a catalyst having the same chemical composition as the nanowire, but prepared from bulk material). In some embodiments, the nanowire having better catalytic properties than a corresponding bulk catalyst has a ratio of effective length to actual length equal to one. In other embodiments, the nanowire having better catalytic properties than a corresponding bulk catalyst has a ratio of effective length to actual length of less than one. In other embodiments, the nanowire having better catalytic properties than a corresponding bulk catalyst comprises one or more elements from Groups 1 through 7, lanthanides or actinides.

Nanowires may be useful in any number of reactions catalyzed by a heterogeneous catalyst. Examples of reactions wherein nanowires having catalytic activity may be employed are disclosed in Farrauto and Bartholomew, “Fundamentals of Industrial Catalytic Processes” Blackie Academic and Professional, first edition, 1997, which is hereby incorporated in its entirety. Other non-limiting examples of reactions wherein nanowires having catalytic activity may be employed include: the oxidative coupling of methane (OCM) to ethane and ethylene; oxidative dehydrogenation (ODH) of alkanes to the corresponding alkenes, for example oxidative dehydrogenation of ethane or propane to ethylene or propylene, respectively; selective oxidation of alkanes, alkenes, and alkynes; oxidation of CO, dry reforming of methane, selective oxidation of aromatics; Fischer-Tropsch, hydrocarbon cracking; combustion of hydrocarbons and the like. Reactions catalyzed by the disclosed nanowires are discussed in more detail below.

The nanowires are generally useful as catalysts in methods for converting a first carbon-containing compound (e.g., a hydrocarbon, CO or CO₂) to a second carbon-containing compound. In some embodiments the methods comprise contacting a nanowire, or material comprising the same, with a gas comprising a first carbon-containing compound and an oxidant to produce a carbon-containing compound. In some embodiments, the first carbon-containing compound is a hydrocarbon, CO, CO₂, methane, ethane, propane, hexane, cyclohexane, octane or combinations thereof. In other embodiments, the second carbon-containing compound is a hydrocarbon, CO, CO₂, ethane, ethylene, propane, propylene, hexane, hexane, cyclohexene, bicyclohexane, octane, octane or hexadecane. In some embodiments, the oxidant is oxygen, ozone, nitrous oxide, nitric oxide, water or combinations thereof.

In other embodiments of the foregoing, the method for conversion of a first carbon-containing compound to a second carbon-containing compound is performed at a temperature below 100° C., below 200° C., below 300° C., below 400° C., below 500° C., below 600° C., below 700° C., below 800° C., below 900° C. or below 1000° C. In other embodiments, the method for conversion of a first carbon-containing compound to a second carbon-containing compound is performed at a pressure below 1 ATM, below 2 ATM, below 5 ATM, below 10 ATM, below 25 ATM or below 50 ATM.

The catalytic reactions described herein can be performed using standard laboratory equipment known to those of skill in the art, for example as described in U.S. Pat. No. 6,350,716, which is incorporated herein in its entirety.

As noted above, the nanowires disclosed herein have better catalytic activity than a corresponding bulk catalyst. In some embodiments, the selectivity, yield, conversion, or combinations thereof, of a reaction catalyzed by the nanowires is better than the selectivity, yield, conversion, or combinations thereof, of the same reaction catalyzed by a corresponding bulk catalyst under the same conditions. For example, in some embodiments, the nanowire possesses a catalytic activity such that conversion of reactant to product in a reaction catalyzed by the nanowire is greater than at least 1.1 times, greater than at least 1.25 times, greater than at least 1.5 times, greater than at least 2.0 times, greater than at least 3.0 times or greater than at least 4.0 times the conversion of reactant to product in the same reaction catalyzed by a catalyst prepared from bulk material having the same chemical composition as the nanowire.

In other embodiments, the nanowire possesses a catalytic activity such that selectivity for product in a reaction catalyzed by the nanowire is greater than at least 1.1 times, greater than at least 1.25 times, greater than at least 1.5 times, greater than at least 2.0 times, greater than at least 3.0 times, or greater than at least 4.0 times the selectivity for product in the same reaction under the same conditions but catalyzed by a catalyst prepared from bulk material having the same chemical composition as the nanowire.

In yet other embodiments, the nanowire possesses a catalytic activity such that yield of product in a reaction catalyzed by the nanowire is greater than at least 1.1 times, greater than at least 1.25 times, greater than at least 1.5 times, greater than at least 2.0 times, greater than at least 3.0 times, or greater than at least 4.0 times the yield of product in the same reaction under the same conditions but catalyzed by a catalyst prepared from bulk material having the same chemical composition as the nanowire.

In certain reactions (e.g., OCM), production of unwanted oxides of carbon (e.g., CO and CO₂) is a problem that reduces overall yield of desired product and results in an environmental liability. Accordingly, in one embodiment the present disclosure addresses this problem and provides nanowires with a catalytic activity such that the selectivity for CO and/or CO₂ in a reaction catalyzed by the nanowires is less than the selectivity for CO and/or CO₂ in the same reaction under the same conditions but catalyzed by a corresponding bulk catalyst. Accordingly, in one embodiment, the present disclosure provides a nanowire which possesses a catalytic activity such that selectivity for CO_(x), wherein x is 1 or 2, in a reaction catalyzed by the nanowire is less than at least 0.9 times, less than at least 0.8 times, less than at least 0.5 times, less than at least 0.2 times or less than at least 0.1 times the selectivity for CO_(x) in the same reaction under the same conditions but catalyzed by a catalyst prepared from bulk material having the same chemical composition as the nanowire.

In some embodiments, the absolute selectivity, yield, conversion, or combinations thereof, of a reaction catalyzed by the nanowires disclosed herein is better than the absolute selectivity, yield, conversion, or combinations thereof, of the same reaction under the same conditions but catalyzed by a corresponding bulk catalyst. For example, in some embodiments the yield of product in a reaction catalyzed by the nanowires is greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%. In other embodiments, the selectivity for product in a reaction catalyzed by the nanowires is greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%. In other embodiments, the conversion of reactant to product in a reaction catalyzed by the nanowires is greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In addition to the improved catalytic performance of the disclosed nanowires, the morphology of the nanowires is expected to provide for improved mixing properties for the nanowires compared to standard colloidal (e.g., bulk) catalyst materials. The improved mixing properties are expected to improve the performance of any number of catalytic reactions, for example, in the area of transformation of heavy hydrocarbons where transport and mixing phenomena are known to influence the catalytic activity. In other reactions, the shape of the nanowires is expected to provide for good blending, reduce settling, and provide for facile separation of any solid material.

In some other chemical reactions, the nanowires are useful for absorption and/or incorporation of a reactant used in chemical looping. For example, the nanowires find utility as NOx traps, in unmixed combustion schemes, as oxygen storage materials, as CO₂ sorption materials (e.g., cyclic reforming with high H2 output) and in schemes for conversion of water to H2.

1. Oxidative Coupling of Methane (OCM)

As noted above, the present disclosure provides nanowires having catalytic activity and related approaches to nanowire design and preparation for improving the yield, selectivity and/or conversion of any number of catalyzed reactions, including the OCM reaction. As mentioned above, there exists a tremendous need for catalyst technology capable of addressing the conversion of methane into high value chemicals (e.g., ethylene and products prepared therefrom) using a direct route that does not go through syngas. Accomplishing this task will dramatically impact and redefine a non-petroleum based pathway for feedstock manufacturing and liquid fuel production yielding reductions in GHG emissions, as well as providing new fuel sources.

Ethylene has the largest carbon footprint compared to all industrial chemical products in part due to the large total volume consumed into a wide range of downstream important industrial products including plastics, surfactants and pharmaceuticals. In 2008, worldwide ethylene production exceeded 120 M metric tons while growing at a robust rate of 4% per year. The United States represents the largest single producer at 28% of the world capacity. Ethylene is primarily manufactured from high temperature cracking of naphtha (e.g., oil) or ethane that is separated from natural gas. The true measurement of the carbon footprint can be difficult as it depends on factors such as the feedstock and the allocation as several products are made and separated during the same process. However, some general estimates can be made based on published data.

Cracking consumes a significant portion (about 65%) of the total energy used in ethylene production and the remainder is for separations using low temperature distillation and compression. The total tons of CO₂ emission per ton of ethylene are estimated at between 0.9 to 1.2 from ethane cracking and 1 to 2 from naphtha cracking. Roughly, 60% of ethylene produced is from naphtha, 35% from ethane and 5% from others sources (Ren, T.; Patel, M. Res. Conserv. Recycl. 53:513, 2009). Therefore, based on median averages, an estimated amount of CO₂ emissions from the cracking process is 114M tons per year (based on 120M tons produced). Separations would then account for an additional 61M tons CO₂ per year.

Nanowires provide an alternative to the need for the energy intensive cracking step. Additionally, because of the high selectivity of the nanowires, downstream separations are dramatically simplified, as compared to cracking which yields a wide range of hydrocarbon products. The reaction is also exothermic so it can proceed via an autothermal process mechanism. Overall, it is estimated that up to a potential 75% reduction in CO₂ emission compared to conventional methods could be achieved. This would equate to a reduction of one billion tons of CO₂ over a ten-year period and would save over 1M barrels of oil per day.

The nanowires also permit converting ethylene into liquid fuels such as gasoline or diesel, given ethylene's high reactivity and numerous publications demonstrating high yield reactions, in the lab setting, from ethylene to gasoline and diesel. On a life cycle basis from well to wheel, recent analysis of methane to liquid (MTL) using F-T process derived gasoline and diesel fuels has shown an emission profile approximately 20% greater to that of petroleum based production (based on a worst case scenario) (Jaramillo, P., Griffin, M., Matthews, S., Env. Sci. Tech 42:7559, 2008). In the model, the CO₂ contribution from plant energy was a dominating factor at 60%. Thus, replacement of the cracking and F-T process would be expected to provide a notable reduction in net emissions, and could be produced at lower CO₂ emissions than petroleum based production.

Furthermore, a considerable portion of natural gas is found in regions that are remote from markets or pipelines. Most of this gas is flared, re-circulated back into oil reservoirs, or vented given its low economic value. The World Bank estimates flaring adds 400M metric tons of CO₂ to the atmosphere each year as well as contributing to methane emissions. The nanowires of this disclosure also provide economic and environmental incentive to stop flaring. Also, the conversion of methane to fuel has several environmental advantages over petroleum-derived fuel. Natural gas is the cleanest of all fossil fuels, and it does not contain a number of impurities such as mercury and other heavy metals found in oil. Additionally, contaminants including sulfur are also easily separated from the initial natural gas stream. The resulting fuels burn much cleaner with no measurable toxic pollutants and provide lower emissions than conventional diesel and gasoline in use today.

In view of its wide range of applications, the nanowires of this disclosure can be used to not only selectively activate alkanes, but also to activate other classes of inert unreactive bonds, such as C—F, C—Cl or C—O bonds. This has importance, for example, in the destruction of man-made environmental toxins such as CFCs, PCBs, dioxins and other pollutants. Accordingly, while the invention is described in greater detail below in the context of the OCM reaction and other the other reactions described herein, the nanowire catalysts are not in any way limited to this particular reaction.

The selective, catalytic oxidative coupling of methane to ethylene (i.e. the OCM reaction) is shown by the following reaction (1):

2CH₄+O₂→CH₂CH₂+2 H₂O   (1)

This reaction is exothermic (Heat of Reaction −67 kcals/mole) and usually occurs at very high temperatures (>700° C.). During this reaction, it is believed that the methane (CH₄) is first oxidatively coupled into ethane (C₂H₆), and subsequently the ethane (C₂H₆) is oxidatively dehydrogenated into ethylene (C₂H₄). Because of the high temperatures used in the reaction, it has been suggested that the ethane is produced mainly by the coupling in the gas phase of the surface-generated methyl (CH₃) radicals. Reactive metal oxides (oxygen type ions) are apparently required for the activation of CH₄ to produce the CH₃ radicals. The yield of C₂H₄ and C₂H₆ is limited by further reactions in the gas phase and to some extent on the catalyst surface. A few of the possible reactions that occur during the oxidation of methane are shown below as reactions (2) through (8):

CH₄→CH₃ radical   (2)

CH₃ radical→C₂H₆   (3)

CH₃ radical+2.5O₂→CO₂+1.5 H₂O   (4)

C₂H₆→C₂H₄+H₂   (5)

C₂H₆+0.5O₂→C₂H₄+H₂O   (6)

C₂H₄+3O₂→2CO₂+2H₂O   (7)

CH₃ radical+C_(x)H_(y)+O₂→Higher HC's -Oxidation/CO₂+H₂O   (8)

With conventional heterogeneous catalysts and reactor systems, the reported performance is generally limited to <25% CH₄ conversion at <80% combined C₂ selectivity, with the performance characteristics of high selectivity at low conversion, or the low selectivity at high conversion. In contrast, the nanowires of this disclosure are highly active and can optionally operate at a much lower temperature. In one embodiment, the nanowires disclosed herein enable efficient conversion of methane to ethylene in the OCM reaction at temperatures less than when the corresponding bulk material is used as a catalyst. For example, in one embodiment, the nanowires disclosed herein enable efficient conversion (i.e., high yield, conversion, and/or selectivity) of methane to ethylene at temperatures of less than 900° C., less than 800° C., less than 700° C., less than 600° C., or less than 500° C. In other embodiments, the use of staged oxygen addition, designed heat management, rapid quench and/or advanced separations may also be employed.

Typically, the OCM reaction is run in a mixture of oxygen and nitrogen or other inert gas. Such gasses are expensive and increase the overall production costs associated with preparation of ethylene or ethane from methane. However, the present inventors have now discovered that such expensive gases are not required and high yield, conversion, selectivity, etc. can be obtained when air is used as the gas mixture instead of pre-packaged and purified sources of oxygen and other gases. Accordingly, in one embodiment the disclosure provides a method for performing the OCM reaction in air. In these embodiments, the catalyst

Accordingly, in one embodiment a stable, very active, high surface area, multifunctional nanowire catalyst is disclosed having active sites that are isolated and precisely engineered with the catalytically active metal centers/sites in the desired proximity (see, e.g., FIG. 1).

The exothermic heats of reaction (free energy) follows the order of reactions depicted above and, because of the proximity of the active sites, will mechanistically favor ethylene formation while minimizing complete oxidation reactions that form CO and CO₂. Representative nanowire compositions useful for the OCM reaction include, but are not limited to: highly basic oxides selected from the early members of the Lanthanide oxide series; Group 1 or 2 ions supported on basic oxides, such as Li/Mg0, Ba/Mg0 and Sr/La₂O₃; and single or mixed transition metal oxides, such as VO_(x) and Re/Ru that may also contain Group 1 ions. Other nanowire compositions useful for the OCM reaction comprise any of the compositions disclosed herein, for example MgO, La₂O₃, Na₂WO₄, Mn₂O₃, Mn₃O₄, Mg₆MnO₈, Zr₂Mo₂O₈, NaMnO₄, Mn₂O₃/Na₂WO₄, Mn₃O₄/Na₂WO₄ or Na/MnO₄/MgO, Mn/WO₄, Nd₂O₃, Sm₂O₂, Eu₂O₃ or combinations thereof. Activating promoters (i.e., dopants), such as chlorides, nitrates and sulfates, or any of the dopants described above may also be employed.

As noted above, the OCM reaction employing known bulk catalysts suffers from poor yield, selectivity, or conversion. In contrast to a corresponding bulk catalyst, Applicants have found that certain nanowires, for example the exemplary nanowires disclosed herein, posses a catalytic activity in the OCM reaction such that the yield, selectivity, and/or conversion is better than when the OCM reaction is catalyzed by a corresponding bulk catalyst. In one embodiment, the disclosure provides a nanowire having a catalytic activity such that the conversion of methane to ethylene in the oxidative coupling of methane reaction is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the conversion of methane to ethylene compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the conversion of methane to ethylene in an OCM reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the yield of ethylene in the oxidative coupling of methane reaction is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the yield of ethylene compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the yield of ethylene in an OCM reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity in the OCM reaction such that the nanowire has the same catalytic activity, but at a lower temperature, compared a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the catalytic activity of the nanowires in the OCM reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 20° C. less. In some embodiments the catalytic activity of the nanowires in the OCM reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 50° C. less. In some embodiments the catalytic activity of the nanowires in the OCM reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 100° C. less. In some embodiments the catalytic activity of the nanowires in the OCM reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 200° C. less.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the selectivity for CO or CO₂ in the oxidative coupling of methane reaction is less than at least 0.9 times, 0.8 times, 0.5 times, 0.2 times, or 0.1 times the selectivity for CO or CO₂ compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire.

In some other embodiments, a method for converting methane into ethylene comprising use of catalyst mixture comprising two or more catalysts is provided. For example, the catalyst mixture may be a mixture of a catalyst having good OCM activity and a catalyst having good ODH activity. Such catalyst mixture are described in more detail above.

2. Oxidative Dehydrogenation

Worldwide demand for alkenes, especially ethylene and propylene, is high. The main sources for alkenes include steam cracking, fluid-catalytic-cracking and catalytic dehydrogenation. The current industrial processes for producing alkenes, including ethylene and propylene, suffer from some of the same disadvantages described above for the OCM reaction. Accordingly, a process for the preparation of alkenes which is more energy efficient and has higher yield, selectivity, and conversion than current processes is needed. Applicants have now found that nanowires, for example the exemplary nanowires disclosed herein, fulfill this need and provide related advantages.

In one embodiment, the disclosed nanowires are useful as catalysts for the oxidative dehydrogenation (ODH) of hydrocarbons (e.g. alkanes, alkenes, and alkynes). For example, in one embodiment the nanowires are useful as catalysts in an ODH reaction for the conversion of ethane or propane to ethylene or propylene, respectively. Reaction scheme (9) depicts the oxidative dehydrogenation of hydrocarbons:

C_(x)H_(y)+½O₂→C_(x)H_(y-2)+H₂O   (9)

Representative catalysts useful for the ODH reaction include, but are not limited to nanowires comprising Zr, V, Mo, Ba, Nd, Ce, Ti, Mg, Nb, La, Sr, Sm, Cr, W, Y or Ca or oxides or combinations thereof. Activating promoters (i.e. dopants) comprising P, K, Ca, Ni, Cr, Nb, Mg, Au, Zn, or Mo, or combinations thereof, may also be employed.

As noted above, improvements to the yield, selectivity, and/or conversion in the ODH reaction employing bulk catalysts are needed. Accordingly, in one embodiment, the present disclosure provides a nanowire which posses a catalytic activity in the ODH reaction such that the yield, selectivity, and/or conversion is better than when the ODH reaction is catalyzed by a corresponding bulk catalyst. In one embodiment, the disclosure provides a nanowire having a catalytic activity such that the conversion of hydrocarbon to alkene in the ODH reaction is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the conversion of methane to ethylene compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the conversion of hydrocarbon to alkene in an ODH reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the yield of alkene in an ODH reaction is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the yield of ethylene compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the yield of alkene in an ODH reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity in the ODH reaction such that the nanowire has the same catalytic activity, but at a lower temperature, compared a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the catalytic activity of the nanowires in the ODH reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 20° C. less. In some embodiments the catalytic activity of the nanowires in the ODH reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 50° C. less. In some embodiments the catalytic activity of the nanowires in the ODH reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 100° C. less. In some embodiments the catalytic activity of the nanowires in the ODH reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 200° C. less.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the selectivity for alkenes in an ODH reaction is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the selectivity for ethylene compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the selectivity for alkenes in an ODH reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the selectivity for CO or CO₂ in an ODH reaction is less than at least 0.9 times, 0.8 times, 0.5 times, 0.2 times, or 0.1 times the selectivity for CO or CO₂ compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire.

In one embodiment, the nanowires disclosed herein enable efficient conversion of hydrocarbon to alkene in the ODH reaction at temperatures less than when the corresponding bulk material is used as a catalyst. For example, in one embodiment, the nanowires disclosed herein enable efficient conversion (i.e. high yield, conversion, and/or selectivity) of hydrocarbon to alkene at temperatures of less than 800° C., less than 700° C., less than 600° C., less than 500° C., less than 400° C., or less than 300° C.

3. Carbon dioxide reforming of methane

Carbon dioxide reforming (CDR) of methane is an attractive process for converting CO₂ in process streams or naturally occurring sources into the valuable chemical product, syngas (a mixture of hydrogen and carbon monoxide). Syngas can then be manufactured into a wide range of hydrocarbon products through processes such as the Fischer-Tropsch synthesis (discussed below) to form liquid fuels including methanol, ethanol, diesel, and gasoline. The result is a powerful technique to not only remove CO₂ emissions but also create a new alternative source for fuels that are not derived from petroleum crude oil. The CDR reaction with methane is exemplified in reaction scheme (10).

CO₂+CH₄→2CO+2H₂   (10)

Unfortunately, no established industrial technology for CDR exists today in spite of its tremendous potential value. While not wishing to be bound by theory, it is thought that the primary problem with CDR is due to side-reactions from catalyst deactiviation induced by carbon deposition via the Boudouard reaction (reaction scheme (11)) and/or methane cracking (reaction scheme (12)) resulting from the high temperature reaction conditions. The occurrence of the coking effect is intimately related to the complex reaction mechanism, and the associated reaction kinetics of the catalysts employed in the reaction.

2CO→C+CO₂   (11)

CH₄→C+2H₂   (12)

While not wishing to be bound by theory, the CDR reaction is thought to proceed through a multistep surface reaction mechanism. FIG. 9 schematically depicts a CDR reaction 700, in which activation and dissociation of CH₄ occurs on the metal catalyst surface 710 to form intermediate “M-C”. At the same time, absorption and activation of CO₂ takes place at the oxide support surface 720 to provide intermediate “S—CO₂”, since the carbon in a CO₂ molecule as a Lewis acid tends to react with the Lewis base center of an oxide. The final step is the reaction between the M-C species and the activated S—CO₂ to form CO.

In one embodiment, the present disclosure provides nanowires, for example the exemplary nanowires disclosed herein, which are useful as catalysts for the carbon dioxide reforming of methane. For example, in one embodiment the nanowires are useful as catalysts in a CDR reaction for the production of syn gas.

Improvements to the yield, selectivity, and/or conversion in the CDR reaction employing bulk catalysts are needed. Accordingly, in one embodiment, the nanowires posses a catalytic activity in the CDR reaction such that the yield, selectivity, and/or conversion is better than when the CDR reaction is catalyzed by a corresponding bulk catalyst. In one embodiment, the disclosure provides a nanowire having a catalytic activity such that the conversion of CO₂ to CO in the CDR reaction is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the conversion of CO₂ to CO compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the conversion of CO₂ to CO in a CDR reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the yield of CO in a CDR reaction is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the yield of CO compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the yield of CO in a CDR reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity in a CDR reaction such that the nanowire has the same catalytic activity, but at a lower temperature, compared a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the catalytic activity of the nanowires in a CDR reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 20° C. less. In some embodiments the catalytic activity of the nanowires in a CDR reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 50° C. less. In some embodiments the catalytic activity of the nanowires in a CDR reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 100° C. less. In some embodiments the catalytic activity of the nanowires in a CDR reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 200° C. less.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the selectivity for CO in a CDR reaction is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the selectivity for CO compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the selectivity for CO in a CDR reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In one embodiment, the nanowires disclosed herein enable efficient conversion of CO₂ to CO in the CDR reaction at temperatures less than when the corresponding bulk material is used as a catalyst. For example, in one embodiment, the nanowires enable efficient conversion (i.e., high yield, conversion, and/or selectivity) of CO₂ to CO at temperatures of less than 900° C., less than 800° C., less than 700° C., less than 600° C., or less than 500° C.

4. Fischer-Tropsch synthesis

Fischer-Tropsch synthesis (FTS) is a valuable process for converting synthesis gas (i.e., CO and H₂) into valuable hydrocarbon fuels, for example, light alkenes, gasoline, diesel fuel, etc. FTS has the potential to reduce the current reliance on the petroleum reserve and take advantage of the abundance of coal and natural gas reserves. Current FTS processes suffer from poor yield, selectivity, conversion, catalyst deactivation, poor thermal efficiency and other related disadvantages. Production of alkanes via FTS is shown in reaction scheme (13), wherein n is an integer.

CO+2H₂→(1/n)(C_(n)H_(2n))+H₂O   (13)

In one embodiment, nanowires are provided which are useful as catalysts in FTS processes. For example, in one embodiment the nanowires are useful as catalysts in a FTS process for the production of alkanes.

Improvements to the yield, selectivity, and/or conversion in FTS processes employing bulk catalysts are needed. Accordingly, in one embodiment, the nanowires posses a catalytic activity in an FTS process such that the yield, selectivity, and/or conversion is better than when the FTS process is catalyzed by a corresponding bulk catalyst. In one embodiment, the disclosure provides a nanowire having a catalytic activity such that the conversion of CO to alkane in an FTS process is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the conversion of CO to alkane compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the conversion of CO to alkane in an FTS process catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity in an FTS process such that the nanowire has the same catalytic activity, but at a lower temperature, compared a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the catalytic activity of the nanowires in an FTS process is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 20° C. less. In some embodiments the catalytic activity of the nanowires in an FTS process is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 50° C. less. In some embodiments the catalytic activity of the nanowires in an FTS process is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 100° C. less. In some embodiments the catalytic activity of the nanowires in an FTS process is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 200° C. less.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the yield of alkane in a FTS process is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the yield of alkane compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the yield of alkane in an FTS process catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the selectivity for alkanes in an FTS process is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the selectivity for alkanes compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the selectivity for alkanes in an FTS process catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In one embodiment, the nanowires disclosed herein enable efficient conversion of CO to alkanes in a CDR process at temperatures less than when the corresponding bulk material is used as a catalyst. For example, in one embodiment, the nanowires enable efficient conversion (i.e., high yield, conversion, and/or selectivity) of CO to alkanes at temperatures of less than 400 ° C., less than 300° C., less than 250° C., less than 200° C., less the 150° C., less than 100° C. or less than 50° C.

5. Oxidation of CO

Carbon monoxide (CO) is a toxic gas and can convert hemoglobin to carboxyhemoglobin resulting in asphyxiation. Dangerous levels of CO can be reduced by oxidation of CO to CO₂ as shown in reaction scheme 14:

CO+½O₂→CO₂   (14)

Catalysts for the conversion of CO into CO₂ have been developed but improvements to the known catalysts are needed. Accordingly in one embodiment, the present disclosure provides nanowires useful as catalysts for the oxidation of CO to CO₂.

In one embodiment, the nanowires posses a catalytic activity in a process for the conversion of CO into CO₂ such that the yield, selectivity, and/or conversion is better than when the oxidation of CO into CO₂ is catalyzed by a corresponding bulk catalyst. In one embodiment, the disclosure provides a nanowire having a catalytic activity such that the conversion of CO to CO₂ is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the conversion of CO to CO₂ compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material and having the same chemical composition as the nanowire. In other embodiments, the conversion of CO to CO₂ catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the yield of CO₂ from the oxidation of CO is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the yield of CO₂ compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the yield of CO₂ from the oxidation of CO catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity in an oxidation of CO reaction such that the nanowire has the same catalytic activity, but at a lower temperature, compared a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the catalytic activity of the nanowires in an oxidation of CO reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 20° C. less. In some embodiments the catalytic activity of the nanowires in an oxidation of CO reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 50° C. less. In some embodiments the catalytic activity of the nanowires in an oxidation of CO reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 100° C. less. In some embodiments the catalytic activity of the nanowires in an oxidation of CO reaction is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 200° C. less.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the selectivity for CO₂ in the oxidation of CO is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the selectivity for CO₂ compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the selectivity for CO₂ in the oxidation of CO catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In one embodiment, the nanowires disclosed herein enable efficient conversion of CO to CO₂ at temperatures less than when the corresponding bulk material is used as a catalyst. For example, in one embodiment, the nanowires enable efficient conversion (i.e., high yield, conversion, and/or selectivity) of CO to CO₂ at temperatures of less than 500° C., less than 400° C., less than 300° C., less than 200° C., less than 100° C., less than 50° C. or less than 20° C.

Although various reactions have been described in detail, the disclosed nanowires are useful as catalysts in a variety of other reactions. In general, the disclosed nanowires find utility in any reaction utilizing a heterogeneous catalyst and have a catalytic activity such that the yield, conversion, and/or selectivity in reaction catalyzed by the nanowires is better than the yield, conversion and/or selectivity in the same reaction catalyzed by a corresponding bulk catalyst.

6. Combustion of Hydrocarbons

In another embodiment, the present disclosure provides a nanowire having catalytic activity in a reaction for the catalyzed combustion of hydrocarbons. Such catalytic reactions find utility in catalytic converters for automobiles, for example by sooth reduction on diesel engines by catalytically burn unused hydrocarbons emitted from the engine when it's running “cold” and thus the engine efficiency in burning hydrocarbons is not very good. When running “cold”, the exhausts of a diesel engine are quite low, thus a low temperature, such as the disclosed nanowires, catalyst is needed to efficiently eliminate all unburned hydrocarbons.

In contrast to a corresponding bulk catalyst, Applicants have found that certain nanowires, for example the exemplary nanowires disclosed herein, posses a catalytic activity in the combustion of hydrocarbons such that the yield, selectivity, and/or conversion is better than when the combustion of hydrocarbons is catalyzed by a corresponding bulk catalyst. In one embodiment, the disclosure provides a nanowire having a catalytic activity such that the combustion of hydrocarbons is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the combustion of hydrocarbons compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In other embodiments, the total combustion of hydrocarbons catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity such that the yield of combusted hydrocarbon products is greater than at least 1.1 times, 1.25 times, 1.50 times, 2.0 times, 3.0 times, or 4.0 times the yield of combusted hydrocarbon products compared to the same reaction under the same conditions but performed with a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the yield of combusted hydrocarbon products in a reaction catalyzed by the nanowire is greater than 10%, greater than 20%, greater than 30%, greater than 50%, greater than 75%, or greater than 90%.

In another embodiment, the disclosure provides a nanowire having a catalytic activity in the combustion of hydrocarbons such that the nanowire has the same catalytic activity, but at a lower temperature, compared a catalyst prepared from bulk material having the same chemical composition as the nanowire. In some embodiments the catalytic activity of the nanowires in the combustion of hydrocarbons is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 20° C. less. In some embodiments the catalytic activity of the nanowires in the combustion of hydrocarbons is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 50° C. less. In some embodiments the catalytic activity of the nanowires in the combustion of hydrocarbons is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 100° C. less. In some embodiments the catalytic activity of the nanowires in the combustion of hydrocarbons is the same as the catalytic activity of a catalyst prepared from bulk material having the same chemical composition as the nanowire, but at a temperature of at least 200° C. less.

7. Evaluation of Catalytic Properties

To evaluate the catalytic properties of the nanowires in a given reaction, for example those reactions discussed above, various methods can be employed to collect and process data including measurements of the kinetics and amounts of reactants consumed and the products formed. In addition to allowing for the evaluation of the catalytic performances, the data can also aid in designing large scale reactors, experimentally validating models and optimizing the catalytic process.

One exemplary methodology for collecting and processing data is depicted in FIG. 10. Three main steps are involved. The first step (block 750) comprises the selection of a reaction and catalyst. This influences the choice of reactor and how it is operated, including batch, flow, etc. (block 754). Thereafter, the data of the reaction are compiled and analyzed (block 760) to provide insights to the mechanism, rates and process optimization of the catalytic reaction. In addition, the data provide useful feed backs for further design modifications of the reaction conditions. Additional methods for evaluating catalytic performance in the laboratory and industrial settings are described in, for example, Bartholomew, C. H. et al. Fundamentals of Industrial Catalytic Processes, Wiley-AlChE; 2Ed (1998).

As an example, in a laboratory setting, an Altamira Benchcat 200 can be employed using a 4 mm ID diameter quartz tube with a 0.5 mm ID capillary downstream. Quartz tubes with 2 mm or 6 mm ID can also be used. Nanowires are tested in a number of different dilutions and amounts. In some embodiments, the range of testing is between 10 and 300 mg. In some embodiments, the nanowires are diluted with a non-reactive diluent. This diluent can be quartz (SiO₂) or other inorganic materials which are known to be inert in the reaction condition. The purpose of the diluent is to minimize hot spots and provide an appropriate loading into the reactor. In addition, the catalyst can be blended with less catalytically active components as described in more detail above.

In a typical procedure, 100 mg is the total charge of nanowire, optionally including diluent. On either side of the nanowires a small plug of glass wool is loaded to keep the nanowires in place. A thermocouple is placed on the inlet side of the nanowire bed into the glass wool to get the temperature in the reaction zone. Another thermocouple can be placed on the downstream end of the nanowire bed into the catalyst bed itself to measure the exotherms, if any.

When blending the pure nanowire with diluent, the following exemplary procedure may be used: x (usually 10-50) mg of the catalyst (either bulk or test nanowire catalyst) is blended with (100-x) mg of quartz (SiO₂). Thereafter, about 2 ml of ethanol or water is added to form a slurry mixture, which is then sonicated for about 10 minutes. The slurry is then dried in an oven at about 100-140° C. for 2 hours to remove solvent. The resulting solid mixture is then scraped out and loaded into the reactor between the plugs of quartz wool.

Once loaded into the reactor, the reactor is inserted into the Altamira instrument and furnace and then a temperature and flow program is started. In some embodiment, the total flow is 50 to 100 sccm of gases but this can be varied and programmed with time. In one embodiment, the temperatures range from 450° C. to 900° C. The reactant gases comprise air or oxygen (diluted with nitrogen or argon) and methane in the case of the OCM reaction and gas mixtures comprising ethane and/or propane with oxygen for oxidative dehydrogenation (ODH) reactions. Other gas mixtures can be used for other reactions.

The primary analysis of these oxidation catalysis runs is the Gas Chromatography (GC) analysis of the feed and effluent gases. From these analyses, the conversion of the oxygen and alkane feed gases can easily be attained and estimates of yields and selectivities of the products and by-products can be determined.

The GC method developed for these experiments employs 4 columns and 2 detectors and a complex valve switching system to optimize the analysis. Specifically, a flame ionization detector (FID) is used for the analysis of the hydrocarbons only. It is a highly sensitive detector that produces accurate and repeatable analysis of methane, ethane, ethylene, propane, propylene and all other simple alkanes and alkenes up to five carbons in length and down to ppm levels.

There are two columns in series to perform this analysis, the first is a stripper column (alumina) which traps polar materials (including the water by-product and any oxygenates generated) until back-flushed later in the cycle. The second column associated with the FID is a capillary alumina column known as a PLOT column which performs the actual separation of the light hydrocarbons. The water and oxygenates are not analyzed in this method.

For the analysis of the light non-hydrocarbon gases, a Thermal Conductivity Detector (TCD) may be employed which also employees two columns to accomplish its analysis. The target molecules for this analysis are CO₂, ethylene, ethane, hydrogen, oxygen, nitrogen, methane and CO. The two columns used here are a porous polymer column known as the Hayes Sep N which performs some of the separation for the CO₂, ethylene and ethane. The second column is a molecular sieve column which uses size differentiation to perform the separation. It is responsible for the separation of H₂, O₂, N₂, methane and CO.

There is a sophisticated and timing sensitive switching between these two columns in the method. In the first 2 minutes or so, the two columns are operating in series but at about 2 minutes, the molecular sieve column is by-passed and the separation of the first 3 components is completed. At about 5-7 minutes, the columns are then placed back in series and the light gases come off of the sieve according to their molecular size.

The end result is an accurate analysis of all of the aforementioned components from these fixed-bed, gas phase reactions. Analysis of other reactions and gases not specifically described above can be performed in a similar manner.

8. Downstream Products

As noted above, in one embodiment the present disclosure is directed to nanowires useful as catalysts in reactions for the preparation of a number of valuable hydrocarbon compounds. For example, in one embodiment the nanowires are useful as catalysts for the preparation of ethylene from methane via the OCM reaction. In another embodiment, the nanowires are useful as catalysts for the preparation of ethylene or propylene via oxidative dehydrogenation of ethane or propane, respectively. Ethylene and propylene are valuable compounds which can be converted into a variety of consumer products. For example, as shown in FIG. 11, ethylene can be converted into many various compounds including low density polyethylene, high density polyethylene, ethylene dichloride, ethylene oxide, ethylbenzene, linear alcohols, vinyl acetate, alkanes, alpha olefins, various hydrocarbon-based fuels, ethanol and the like. These compounds can then be further processed using methods well known to one of ordinary skill in the art to obtain other valuable chemicals and consumer products (e.g. the downstream products shown in FIG. 11). Propylene can be analogously converted into various compounds and consumer goods including polypropylenes, propylene oxides, propanol, and the like.

Accordingly, in one embodiment the disclosure provides a method of preparing the downstream products of ethylene noted in FIG. 11. The method comprises converting ethylene into a downstream product of ethylene, wherein the ethylene has been prepared via a catalytic reaction employing a nanowire, for example any of the nanowires disclosed herein. In another embodiment the disclosure provides a method of preparing low density polyethylene, high density polyethylene, ethylene dichloride, ethylene oxide, ethylbenzene, ethanol or vinyl acetate from ethylene, wherein the ethylene has been prepared as described above.

In another embodiment, the disclosure provides a method of preparing a product comprising low density polyethylene, high density polyethylene, ethylene dichloride, ethylene oxide, ethylbenzene, ethanol or vinyl acetate, alkenes, alkanes, aromatics, alcohols, or mixtures thereof. The method comprises converting ethylene into low density polyethylene, high density polyethylene, ethylene dichloride, ethylene oxide, ethylbenzene, ethanol or vinyl acetate, wherein the ethylene has been prepared via a catalytic reaction employing a nanowires, for example any of the exemplary nanowires disclosed herein.

In more specific embodiments of any of the above methods, the ethylene is produced via an OCM or ODH reaction.

In one particular embodiment, the disclosure provides a method of preparing a downstream product of ethylene and/or ethane, wherein the downstream product is a hydrocarbon fuel. For example, the downstream product of ethylene may be a C₄-C₁₄ hydrocarbon, including alkanes, alkenes and aromatics. Some specific examples include 1-butene, 1-hexene, 1-octene, xylenes and the like. The method comprises converting methane into ethylene, ethane or combinations thereof by use of a catalytic nanowire, for example any of the catalytic nanowires disclosed herein, and further oligomerizing the ethylene and/or ethane to prepare a downstream product of ethylene and/or ethane. For example, the methane may be converted to ethylene, ethane or combinations thereof via the OCM reaction as discussed above. The catalytic nanowire may be any nanowire and is not limited with respect to morphology or composition. The catalytic nanowire may be an inorganic catalytic polycrystalline nanowire, the nanowire having a ratio of effective length to actual length of less than one and an aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the nanowire comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof. Alternatively, the catalytic nanowire may be an inorganic nanowire comprising one or more metal elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof and a dopant comprising a metal element, a semi-metal element, a non-metal element or combinations thereof. The nanowires may additionally comprise any number of doping elements as discussed above.

As depicted in FIG. 21, the method begins with charging methane (e.g., as a component in natural gas) into an OCM reactor. The OCM reaction may then be performed utilizing a nanowire under any variety of conditions. Water and CO₂ are optionally removed from the effluent and unreacted methane is recirculated to the OCM reactor.

Ethylene is recovered and charged to an oligomerization reactor. Optionally the ethylene stream may contain CO₂, H₂O, N₂, ethane, C3's and/or higher hydrocarbons. Oligomerization to higher hydrocarbons (e.g., C₄-C₁₄) then proceeds under any number of conditions known to those of skill in the art. For example oligomerization may be effected by use of any number of catalysts known to those skilled in the art. Examples of such catalysts include catalytic zeolites, crystalline borosilicate molecular sieves, homogeneous metal halide catalysts, Cr catalysts with pyrrole ligands or other catalysts.. Exemplary methods for the conversion of ethylene into higher hydrocarbon products are disclosed in the following references: Catalysis Science & Technology (2011), 1(1), 69-75; Coordination Chemistry Reviews (2011), 255(7-8), 861-880; Eur. Pat. Appl. (2011), EP 2287142 A1 20110223; Organometallics (2011), 30(5), 935-941; Designed Monomers and Polymers (2011), 14(1), 1-23; Journal of Organometallic Chemistry 689 (2004) 3641-3668; Chemistry—A European Journal (2010), 16(26), 7670-7676; Acc. Chem. Res. 2005, 38, 784-793; Journal of Organometallic Chemistry, 695 (10-11): 1541-1549 May 15 2010; Catalysis Today Volume 6, Issue 3, Jan. 1990, Pages 329-349; U.S. Pat. Nos. 5,968,866; 6,800,702; 6,521,806; 7,829,749; 7,867,938; 7,910,670; 7,414,006 and Chem. Commun., 2002, 858-859, each of which are hereby incorporated in their entirety by reference.

In certain embodiments, the exemplary OCM and oligomerization modules depicted in FIG. 21 may be adapted to be at the site of natural gas production, for example a natural gas field. Thus the natural gas can be efficiently converted to more valuable and readily transportable hydrocarbon commodities without the need for transport of the natural gas to a processing facility.

Referring to FIG. 21, “natural gasoline” refers to a mixture of oligomerized ethylene products. The mixture may comprise 1-hexene, 1-octene, linear, branched or cyclic alkanes of 6 or more hydrocarbons, linear, branched, or cyclic alkenes of 6 or more hydrocarbons, aromatics, such as benzene, toluene, dimethyl benzene, xylenes, napthalene, or other oligomerized ethylene products and combinations thereof. This mixture finds particular utility in any number of industrial applications, for example natural gasoline is used as feedstock in oil refineries, as fuel blend stock by operators of fuel terminals, as diluents for heavy oils in oil pipelines and other applications. Other uses for natural gasoline are well-known to those of skill in the art.

EXAMPLES Example 1 Genetic Engineering/Preparation of Phage

Phage were amplified in DH5 derivative E. coli (New England Biolabs, NEB5-alpha F′ Iq; genotype: F′ proA+B+laclq Δ(lacZ)M15 zzf:Tn10 (TetR)/fhuA2Δ(argF-lacZ)U169 phoA gInV44 ϕ 80Δ(lacZ)M15 gyrA96 recA1 endA1 thi-1 hsdR17) and purified using standard polyethylene glycol and sodium chloride precipitation protocols as described in the following references: Kay, B. K.; Winter, J.; McCafferty, J. Phage Display of Peptides and Proteins: A Laboratory Manual; Academic Press: San Diego (1996); C. F. Barbas, et al., ed., Phage Display: A Laboratory Manual; Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., USA (2001); and Joseph Sambrook and David W. Russell, Molecular Cloning, 3rd edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., USA, 2001.

Example 2 Preparation of Phage Solutions

The phage solutions were additionally purified by centrifuging at an acceleration of 10000 g at least once (until no precipitated material was observed), decanting the supernatant and splitting it in 50 ml containers, which were then stored frozen at −20° C. The frozen phage solutions were thawed only shortly before being used.

The concentration of the phage solutions was measured using a UV-VIS spectrometer. The concentration of each of the frozen phage aliquots was measured prior to use. This spectroscopic method relies on the absorption of the nucleotides in the DNA of the phage and is described in more detail in “Phage Display: A Laboratory Manual” by Barbas, Burton, Scott and Silverman (Cold Spring Harbor Laboratory Press, 2001). The concentration of phage solutions is expressed in pfu/ml (plague forming units per milliliter).

Example 3 Preparation Mg(OH)₂ Nanowires

FIG. 12 shows a generic reaction scheme for preparing MgO nanowires (with dopant). First, the phage solution is thawed and its concentration determined according to the method described above. The phage solution is diluted with water to adjust its concentration in the reaction mixture (i.e. with all the ingredients added) to the desired value, typically 5e12 pfu/ml or higher. The reaction container can be anything from a small vial (for milliliter scale reactions) up to large bottles (for liter reaction scale reactions).

A magnesium solution and a base solution are added to the phage solution in order to precipitate Mg(OH)₂. The magnesium solution can be of any soluble magnesium salt, e.g. MgX2.6H2O(X═Cl, Br, I), Mg(NO₃)₂, MgSO₄, magnesium acetate, etc. The range of the magnesium concentration in the reaction mixture is quite narrow, typically at 0.01M. The combination of the phage concentration and the magnesium concentration (i.e. the ratio between the pVIII proteins and magnesium ions) is very important in determining both the nanowires formation process window and their morphology.

The base can be any alkali metal hydroxide (e.g. LiOH, NaOH, KOH), soluble alkaline earth metal hydroxide (e.g. Sr(OH)₂, Ba(OH)₂) or any ammonium hydroxide (e.g., NR₄OH, R═H, CH₃, C₂H₅, etc.). Certain selection criteria for the base include: adequate solubility (at least several orders of magnitude higher than Mg(OH)₂ for Mg(OH)₂ nanowires), high enough strength (pH of the reaction mixture should be at least 11) and an inability to coordinate magnesium (for Mg(OH)₂ nanowires) to form soluble products. LiOH is a preferred choice for Mg(OH)₂ nanowires formation because lithium may additionally be incorporated in the Mg(OH)₂ as a dopant, providing a Li/MgO doped catalyst for OCM.

Another factor concerning the base is the amount of base used or the concentration ratio of OH⁻/Mg²⁺, i.e. the ratio between the number of OH equivalents added and the number of moles of Mg added. In order to fully convert the Mg ions in solution to Mg(OH)₂, the OH/Mg ratio needed is 2. The OH⁻/Mg²⁺ used in the formation of Mg(OH)₂ nanowires ranges from 0.5 to 2 and, depending on this ratio, the morphology of the reaction product changes from thin nanowires to agglomerations of nanoparticles. The OH⁻/Mg²⁺ ratio is determined by the pH of the reaction mixture, which needs to be at least 11. If the pH is below 11, no precipitation is observed, i.e. no Mg(OH)₂ is formed. If the pH is above 12, the morphology of the nanowires begins to change and more nanoparticles are obtained, i.e. non-selective precipitation.

Considering the narrow window of magnesium concentration in which Mg(OH)₂ nanowires can be obtained, the other key synthetic parameters that determine the nanowires formation and morphology include but are not limited to: phage sequence and concentration thereof, the concentration ratio of Mg²⁺/pVIII protein, the concentration ratio of OH⁻/Mg²+, the incubation time of phage and Mg²⁺; incubation time of phage and the OH⁻; the sequence of adding anion and metal ions; pH; the solution temperature in the incubation step and/or growth step; the types of metal precursor salt (e.g., MgCl₂ or Mg(NO₃)₂); the types of anion precursor (e.g., NaOH or LiOH); the number of additions; the time that lapses between the additions of the metal salt and anion precursor, including, e.g., simultaneous (zero lapse) or sequential additions.

The Mg salt solution and the base were added sequentially, separated by an incubation time (i.e., the first incubation time). The sequence of addition has an effect on the morphology of the nanowires. The first incubation time can be at least 1 h and it should be longer in the case the magnesium salt solution is added first. The Mg salt solution and the base can be added in a single “shot” or in a continuous slow flow using a syringe pump or in multiple small shots using a liquid dispenser robot. The reaction is then carried either unstirred or with only mild to moderate stirring for a specific time (i.e., the second incubation time). The second incubation time is not as strong a factor in the synthesis of Mg(OH)₂ nanowires, but it should be long enough for the nanowires to precipitate out of the reaction solution (e.g., several minutes). For practical reasons, the second incubation time can be as long as several hours. The reaction temperature can be anything from just above freezing temperature (e.g., 4° C.) up to 80° C. The temperature affects the nanowires morphology.

The precipitated Mg(OH)₂ nanowires are isolated by centrifuging the reaction mixture and decanting the supernatant. The precipitated material is then washed at least once with a water solution with pH>10 to avoid redissolution of the Mg(OH)₂ nanowires. Typically, the washing solution used can be ammonium hydroxide water solution or an alkali metal hydroxide solution (e.g., LiOH, NaOH, KOH). This mixture is centrifuged and the supernatant decanted. Finally, the product can be either dried (see, Example 5) or resuspended in ethanol for TEM analysis.

The decanted supernatant of the reaction mixture can be analyzed by UV-VIS to determine the phage concentration (see, Example 2) and thus give an estimate of the amount of phage incorporated in the precipitated Mg(OH)₂, i.e. the amount of “mineralized” phage.

FIG. 12 depicts one embodiment for preparing Mg(OH)₂ nanowires. In a different embodiment, the order of addition may be reversed, for example in an exemplary 4 ml scale synthesis of Mg(OH)₂ nanowires, 3.94 ml of concentrated solution of phages (e.g., SEQ ID NO: 3 at a concentration of ˜5E12 pfu/ml) were mixed in a 8 ml vial with 0.02 ml of 1 M LiOH aqueous solution and left incubating overnight (˜15h). 0.04 ml of 1 M MgCl₂ aqueous solution were then added using a pipette and the mixture was mixed by gentle shaking. The reaction mixture was left incubating unstirred for 24 h. After the incubation time, the mixture was centrifuged, and the supernatant was decanted and saved for phage concentration measurement by UV-VIS. The precipitated material was resuspended in 2 ml of 0.001 M LiOH aqueous solution (pH=11), the mixture was centrifuged and the supernatant decanted. The obtained Mg(OH)₂ nanowires were characterized by TEM as described in Example 4.

Example 4 Characterization of Mg(OH)₂ Nanowires

Mg(OH)₂ nanowires prepared according to Example 3 were characterized by TEM in order to determine their morphology. First, a few microliters (˜500) of ethanol was used to suspend the isolated Mg(OH)₂. The nanowires were then deposited on a TEM grid (copper grid with a very thin carbon layer) placed on filter paper to help wick out any extra liquid. After allowing the ethanol to dry, the TEM grid was loaded in a TEM and characterized. TEM was carried out at 5KeV in bright field mode in a DeLong LVEMS.

The nanowires were additionally characterized by XRD (for phase identification) and TGA (for calcination optimization).

Example 5 Calcination of Mg(OH)₂ Nanowires

The isolated nanowires as prepared in Example 3 were dried in an oven at relatively low temperature (60-120° C.) prior to calcination.

The dried material was placed in a ceramic boat and calcined in air at 450 C.° in order to convert the Mg(OH)₂ nanowires into MgO nanowires. The calcination recipe can be varied considerably. For example, the calcination can be done relatively quickly like in these two examples:

load in a muffle oven preheated at 450° C., calcination time=120 min

load in a muffle oven (or tube furnace) at room temperature and ramp to 450° C. with 5° C./min rate, calcination time=60min

Alternatively, the calcination can be done in steps that are chosen according to the TGA signals like in the following example:

load in a muffle oven (or tube furnace) at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 60min, ramp to 280° C. with 2° C./min rate, dwell for 60min, ramp to 350° C. with 2° C./min rate, dwell for 60min and finally ramp to 450° C. with 2° C./min rate, dwell for 60min.

Generally, a step recipe is preferable since it should allow for a better, smoother and more complete conversion of Mg(OH)₂ into MgO. Optionally, the calcined product is ground into a fine powder.

FIG. 13 shows the X-ray diffraction patterns of the Mg(OH₂) nanowires and the MgO nanowires following calcinations. Crystalline structures of both types of nanowires were confirmed.

Example 6 Preparation of Li Doped MgO Nanowires

Doping of nanowires is achieved by using the incipient wetness impregnation method. Before impregnating the MgO nanowires with the doping solution, the maximum wettability (i.e. the ability of the nanowires to absorb the doping solution before becoming a suspension or before “free” liquid is observed) of the nanowires was determined. This is a very important step for an accurate absorption of the doping metal on the MgO surface. If too much dopant solution is added and a suspension is formed, a significant amount of dopant will crystallize unabsorbed upon drying and if not enough dopant solution is added, significant portions of the MgO surface will not be doped.

In order to determine the maximum wettability of the MgO nanowires, small portions of water were dropped on the calcined MgO powder until a suspension was formed, i.e. until “free” liquid is observed. The maximum wettability was determined to be the total amount of water added before the suspension formed. The concentration of the doping solution was then calculated so that the desired amount of dopant was contained in the volume of doping solution corresponding to the maximum wettability of the MgO nanowires. In another way to describe the incipient wetness impregnation method, the volume of the doping solution is set to be equal to the pore volume of the nanowires, which can be determined by BET (Brunauer, Emmett, Teller) measurements. The doping solution is then drawn into the pores by capillary action.

In one embodiment, the doping metal for MgO based catalysts for OCM is lithium (see, also, FIG. 12). Thus, in one embodiment the dopant source can be any soluble lithium salt as long as it does not introduce undesired contaminants. Typically, the lithium salts used were LiNO₃, LiOH or Li₂CO₃. LiNO₃ and LiOH are preferred because of their higher solubility. In one embodiment, the lithium content in MgO catalysts for OCM ranges from 0 to 10 wt % (i.e. about 0 to 56 at %).

The calculated amount of dopant solution of the desired concentration was dropped onto the calcined MgO nanowires. The obtained wet powder was dried in an oven at relatively low temperature (60-120° C.) and calcined using one of the recipes described above. It is noted that, during this step, no phase transition occurs (MgO has already been formed in the previous calcination step) and thus a step recipe (see previous paragraph) may not be necessary.

The dopant impregnation step can also be done prior to the calcination, after drying the Mg(OH)₂ nanowires isolated from the reaction mixture. In this case, the catalyst can be calcined immediately after the dopant impregnation, i.e. no drying and second calcination steps would be required since its goals are accomplished during the calcination step.

Three identical synthesis were made in parallel. In each synthesis, 80 ml of concentrated solution of phages (SEQ ID NO: 3 at a concentration of ≥5E12 pfu/ml) were mixed in a 100 ml glass bottle with 0.4 ml of 1 M LiOH aqueous solution and left incubating for 1 h. 0.8 ml of 1 M MgCl₂ aqueous solution were added using a pipette and the mixture was mixed by gently shaking it. The reaction mixture was left incubating unstirred for 72h at 60° C. in an oven. After the incubation time, the mixture was centrifuged. The precipitated material was resuspended in 20 ml of 0.06 M NH₄OH aqueous solution (pH=11), the mixture was centrifuged and the supernatant decanted. The obtained Mg(OH)₂ nanowires were resuspended in ethanol. The ethanol suspensions of the three identical syntheses were combined and a few microliters of the ethanol suspension were used for TEM analysis. The ethanol suspension was centrifuged and the supernatant decanted. The gel-like product was transferred in a ceramic boat and dried for 1 h at 120° C. in a vacuum oven.

The dried product was calcined in a tube furnace using a step recipe (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 60 min, ramp to 280° C. with 2° C./min rate, dwell for 60 min, ramp to 350° C. with 2° C./min rate, dwell for 60 min, ramp to 450° C. with 2° C./min rate, dwell for 60min and finally cool to room temperature). The yield was 24 mg. The calcined product was ground to a fine powder.

10 mg of the calcined product were impregnated with a LiOH aqueous solution. First, the maximum wettability was determined by adding water to the calcined product in a ceramic boat until the powder was saturated but no “free” liquid was observed. The maximum wettability was 12 μl. Since the target doping level was 1 wt % lithium, the necessary concentration of the LiOH aqueous solution was calculated to be 1.2 M. The calcined product was dried again for 1 h at 120° C. to remove the water used to determine the wettability of the powder. 12 μl of the 1.2 M LiOH solution were dropped on the MgO nanowires powder. The wet powder was dried for 1 h at 120° C. in a vacuum oven and finally calcined in a muffle oven (load at room temperature, ramp to 460° C. with 2° C./min ramp, dwell for 120 min).

Example 7 Creating Diversity by Varying the Reaction Parameters

Certain synthetic parameters strongly influence the nanowire formation on phage, including selective binding of metal and/or anions, as well as surface morphologies. FIG. 14 shows a number of MgO nanowires synthesized in the presence of different phage sequence (e.g., different pVIII) while keeping the other reaction conditions constant. Phages of SEQ ID NOs. 1, 7, 10, 11, 13 and 14 were the respective phage of choice in six reactions carried out in otherwise identical conditions. The constant reaction conditions may include: concentration ratios of Mg²⁺ and active functional groups on the phage; concentration ratios of OH⁻/Mg²⁺; incubation time of phage and Mg²⁺; incubation time of phage and OH⁻; concentration of phage; sequence of adding anion and metal ions; solution temperature in the incubation step and/or growth step; etc. As shown, the morphologies of MgO nanowires are significantly influenced by the phage sequences.

Thus, varying these and other reaction conditions may produce a diverse class of nanowire catalysts. In addition, certain correlation between the reaction conditions and the surface morphologies of the nanowires can be empirically established, thus enabling rational designs of catalytic nanowires.

Example 8 Preparation of Sr-Doped La₂O₃ Nanowires

23 ml of 2.5 e12 pfu solution of phages (SEQ ID NO: 3) was mixed in a 40 ml glass bottle with 0.046 ml of 0.1 M LaCl₃ aqueous solution and left incubating for 16h. After this incubation period, a slow multistep addition is conducted with 1.15 ml of 0.05 M LaCl₃ solution and 1.84 ml of 0.3 M NH₄OH. This addition is conducted in six hours and twenty steps. The reaction mixture was left stirred another 2 h at room temperature. After that time the suspension was centrifuged in order to separate the solid phase from the liquid phase. The precipitated material was then resuspended in 5 ml of water and centrifuged in order to further remove un-reacted species. A final wash was conducted with 2 ml ethanol. The gel-like product remaining is then dried for 30 minutes at 110° C. in a vacuum oven.

The dried product was then calcined in a muffle furnace using a step recipe (load in the furnace at room temperature, ramp to 200° C. with 3° C./min rate, dwell for 120min, ramp to 400° C. with 3° C./min rate, dwell for 120min, cool to room temperature). The calcined product was then ground to a fine powder.

5 mg of the calcined product were impregnated with 0.015 ml Sr(NO₃)₂ 0.1M aqueous solution. Powder and solution is mixed on hot plate at 90C until forming a paste. The paste was then dried for 1 h at 120° C. in a vacuum oven and finally calcined in a muffle oven in air. (load in the furnace at room temperature, ramp to 200° C. with 3° C./min rate, dwell for 120min, ramp to 400° C. with 3° C./min rate, dwell for 120min, ramp to 500° C. with 3° C./min rate, dwell for 120min, cool to room temperature).

Example 9 Preparation of ZrO₂/La₂O₃ Core/Shell Nanowires

As an example, FIG. 15 shows schematically an integrated process 800 for growing a core/shell structure of ZrO₂/La₂O₃ nanowire. A phase solution is prepared, to which a zirconium salt precursor (e.g., ZrCl₂) is added to allow for the nucleation of ZrO²⁺ on the phage. Subsequently, a hydroxide precursor (e.g., LiOH) is added to cause the nucleation of hydroxide ions on the phage. Nanowires 804 is thus formed in which the phage 810 is coated with a continuous and crystalline layer 820 of ZrO(OH)₂. To this reaction mixture, a lanthanum salt precursor (e.g., LaCl₃) is added under a condition to cause the nucleation of La(OH)₃ over the ZrO(OH)₂ nanowire 804. Following calcinations, nanowires of a core/shell structure of ZrO₂/La₂O₃ are formed. A further step of impregnation produces nanowires of ZrO₂/La₂O₃ doped with strontium ions (Sr²⁺) 840, in which the phage 810 is coated with a layer of ZrO₂ 830, which is in turn coated with a shell of La₂O₃ 850.

ZrO₂/La₂O₃ nanowires were thus prepared by mixing 20 ml of 2.5e12 pfu E3 Phage solution to 0.1 ml of 0.5M ZrO(NO₃)₂ aqueous solution. The solution was incubated under stirring for 16 hours. Any solids formed following incubation were removed by centrifugation at 4000 rpm for 5 minutes and redispersed in 0.5 ml ethanol. A small aliquot was retrieved for TEM characterization.

Thereafter, the ethanol solution was mixed with 10 ml water and 2 ml of 0.05M ZrO(NO₃)₂ with 2 ml of 0.1M NH₄OH were added during a period of 200 minutes using syringe pumps. Wash solids with water and resuspend in ethanol for TEM observation.

To about 18 mg of ZrO(OH)₂ nanowires in suspension, 10 ml of water was added, followed by the addition of 0.5 ml of LaCl₃ 0.083 M with 0.5 ml of NH₄OH 0.3 M solution during a period of 50 minutes using syringe pumps. The solids thus formed were separated by centrifugation to obtain a powder, which was dried in a vacuum oven at 110° C. for one hour. A small aliquot of the dried powder is then suspended in ethanol for TEM observation.

Example 10 Preparation of La(OH)₃/ZrO₂ Core/Shell Nanowires

Similar to Example 9, La(OH)₃ nanowires were coated with ZrO₂ shell according to the following process. To 6.8 mg of La(OH)₃ nanowires (prepared by LaCl₃ and NH₄OH in a process similar to that of Example 9), which had been dried at 110° C., was added 4 ml of water to suspend the solids. 0.5 ml of 0.05M ZrO(NO₃)₂ and 0.5 ml of 0.1 M NH₄OH were slowly added in 50 minutes. The solids were retrieved by centrifugation and calcined at 500° C. for one hour. TEM observation showed nanowires as the major morphology.

Example 11 Preparation of Hollow-Cored ZrO₂ Nanowires

To the La(OH)₃/ZrO₂ core/shell nanowires prepared Example 10, additional processing can be used to create hollow ZrO₂ shell nanowires. The La(OH)₃ core can be etched using 1M citric acid solution. Controlled experiments on calcined and un-calcined La(OH)₃ nanowires shows that the entire nanowires are fully etched in about one hour at room temperature. Etching of La(OH)₃/ZrO₂ core/shell nanowires was conducted overnight (about 16 hours).

The remaining solid was then separated by centrifugation and TEM observation is conducted on the washed solids (water wash). Low contrast zirconia nanowires were observed after etching, which indicates that hollow zirconia “straws” can be formed using La(OH)3 nanowire as template.

Example 12 OCM Catalyzed by La₂O₃ Nanowires

A 20 mg sample of a phage-based Sr (5%) doped La₂O₃ catalyst was diluted with 80 mg of quartz sand and placed into a reactor (run WPS21). The gas flows were held constant at 9 sccm methane, 3 sccm oxygen and 6 sccm of argon. The upstream temperature (just above the bed) was varied from 500° C. to 800° C. in 100° C. increments and then decreased back down to 600° C. in 50° C. increments. The vent gas analysis was gathered at each temperature level.

As a point of comparison, 20 mg of bulk 5% Sr on La₂O₃ catalyst was diluted in the same manner and run through the exact flow and temperature protocol.

FIG. 16 shows the formation of OCM products at 700° C., including C2 (ethane and ethylene) as well as further coupling products (propane and propylene).

FIGS. 17A, 17B and 17C show the comparative results in catalytic performance parameters for a nanowire catalyst (Sr²⁺/La₂O₃) vs. its corresponding bulk material (Sr²⁺/La₂O₃ bulk). Methane conversion rates, C2 selectivities and C2 yields are among the important parameters by which the catalytic properties were measured. More specifically, FIG. 17A shows the methane conversion rates are higher for the nanowire catalyst compared to the bulk material across a wide temperature range (e.g., 550 to 650° C.). Likewise, FIG. 17B and FIG. 17C show that the C2 selectivities and C2 yields are also higher for the nanowire catalyst as compared to the bulk catalyst across a wide temperature range (e.g., 550 to 650° C.). Thus, it is demonstrated that by improving both conversion and selectivity simultaneously that the C2 yield can be improved over traditional bulk catalysts.

FIGS. 18A-18B demonstrate that nanowires prepared under different synthetic conditions afforded different catalytic performances, suggesting that the various synthetic parameters resulted in divergent nanowire morphologies. FIG. 18A shows that nanowires prepared using different phage templates (SEQ ID NO: 9 and SEQ ID NO:3) in otherwise identical synthetic conditions created nanowire catalysts that perform differently in terms of the C2 selectivity in an OCM reaction. FIG. 18B shows the comparative C2 selectivities of nanowires prepared by an alternative adjustment of the synthetic parameters. In this case, the phage template was the same for both nanowires (SEQ ID NO:3), but the synthetic conditions were different. Specifically, the nanowires of FIG. 18A were prepared with shorter incubation and growth times than the nanowires of FIG. 18B. Additionally, the nanowires of FIG. 18A were calcined in a single step at 400° C. instead of the ramped temperature calcinations performed on the nanowires of FIG. 18B.

These results confirm that the nanowire catalysts behave differently from their bulk material counterparts. In particular, the nanowire catalysts allow for adjustments of the surface morphologies through synthetic design and screening to ultimately produce high-performance catalysts.

Example 13 Oxidative Dehydrogenation Catalyzed by MgO Nanowires

A 10 mg sample of phage-based Li doped MgO catalyst was diluted with 90 mg of quartz sand and placed in a reactor. The gas flows were held constant at 8 sccm alkane mix, 2 sccm oxygen and 10 sccm of argon. The upstream temperature (just above the bed) was varied from 500° C. to 750° C. in 50-100° C. increments. The vent gas analysis was gathered at each temperature level.

As a point of comparison, 10 mg of bulk 1 wt % Li on MgO catalyst was diluted in the same manner and run through the exact flow and temperature protocol. The results of this experiment are shown in FIG. 19. As can be seen in FIG. 19, phage-based nanowires according to the present disclosure comprise better conversion of ethane and propane compared to a corresponding bulk catalyst.

Example 14 Synthesis of Sr Doped La₂O₃ Nanowires

Sr doped La₂O₃ nanowires were prepared according to the following non-template directed method.

A La(OH)₃ gel was prepared by adding 0.395 g of NH₄OH (25%) to 19.2 ml of water followed by addition of 2 ml of a 1 M solution of La(NO₃)₃. The solution was then mixed vigorously. The solution first gelled but the viscosity dropped with continuous agitation. The solution was then allowed to stand for a period of between 5 and 10 minutes. The solution was then centrifuged at 10,000 g for 5 minutes. The centrifuged gel was retrieved and washed with 30 ml of water and the centrifugation washing procedure was repeated.

To the washed gel was added 10.8 ml of water to suspend the solid. The suspension was then transferred to a hydrothermal bomb (20 ml volume, not stirred). The hydrothermal bomb was then loaded in a muffle furnace at 160° C. and the solution was allowed to stand under autogenous pressure at 160° C. for 16 hours.

The solids were then isolated by centrifugation at 10,000 g for 5 minutes, and wash with 10 ml of water to yield about 260 mg of solid (after drying). The obtained solids were calcined in a muffle oven according to the following procedure: (1) load in the furnace at room temperature; (2) ramp to 200° C. with 3° C./min rate; (3) dwell for 120 min; (4) ramp to 400° C. with 3° C./min rate; and (5) dwell for 120 min. About 220 mg of nanowires were retrieved after calcination.

A 57 mg aliquot of nanowires was then mixed with 0.174 ml of a 0.1 M solution of Sr(NO₃)₂. This mixture was then stirred on a hot plate at 90° C. until a paste was formed.

The paste was then dried for 1 h at 120° C. in a vacuum oven and finally calcined in a muffle oven in air according to the following procedure: (1) load in the furnace at room temperature; (2) ramp to 200° C. with 3° C./min rate; (3) dwell for 120 min; (3) ramp to 400° C. with 3° C./min rate; (4) dwell for 120 min; (5) ramp to 500° C. with 3° C./min rate; and (6) dwell for 120min. The calcined product was then ground to a fine powder.

5 mg of the calcined product were impregnated with 0.015 ml Sr(NO₃)₂ 0.1M aqueous solution. Powder and solution is mixed on hot plate at 90C until forming a paste. The paste was then dried for 1 h at 120° C. in a vacuum oven and finally calcined in a muffle oven in air. (load in the furnace at room temperature, ramp to 200° C. with 3° C./min rate, dwell for 120min, ramp to 400° C. with 3° C./min rate, dwell for 120min, ramp to 500° C. with 3° C./min rate, dwell for 120min).

FIG. 20 shows a TEM image of the nanowires obtained from this non-template directed method. As shown in FIG. 20, the nanowires comprise a ratio of effective length to actual length of about 1 (i.e., the nanowires comprise a “straight” morphology).

Example 15 Synthesis of La₂O₃ Nanowires

La(NO₃)₃.6 H₂O (10.825 g) is added to 250 mL distilled water and stirred until all solids are dissolved. Concentrated ammonium hydroxide (4.885 mL) is added to this mixture and stirred for at least one hour resulting in a white gel. This mixture is transferred equally to 5 centrifuge tubes and centrifuged for at least 15 minutes. The supernatant is discarded and each pellet is rinsed with water, centrifuged for at least 15 minutes and the supernatant is again discarded.

The resulting pellets are all combined, suspended in distilled water (125 mL) and heated at 105° C. for 24 hours. The lanthanum hydroxide is isolated by centrifugation and suspended in ethanol (20 mL). The ethanol supernatant is concentrated and the product is dried at 65° C. until all ethanol is removed.

The lanthanum hydroxide nanowires prepared above are calcined by heating at 100° C. for 30 min., 400° C. for 4 hours and then 550° C. for 4 hours to obtain the La₂O₃ nanowires.

Example 16 Preparation of Na₁₀MnW₅O₁₇ Nanowires

25 ml of concentrated reagent grade NH₄OH are dissolved in 25 ml of distilled water, and 1 ml of 0.001M aqueous solution of M13 bacteriophage is then added. 0.62 g of Mn(NO₃)₂, 1.01 g of NaCl and 2.00 g of WO₃ are then added to the mixture with stirring. The mixture is heated at a temperature of about 95° C. for 15 minutes. The mixture is then dried overnight at about 110° C. and calcined at about 400° C. for 3 hours.

Example 17 Preparation of Na₁₀MnW₅O₁₇ Nanowires

25 ml of concentrated reagent grade NH₄OH are dissolved in 25 ml of distilled water, and 1 ml of 0.001 M aqueous solution of M13 bacteriophage is then added. 1.01 g of NaCl and 2.00 g of WO₃ are then added to the mixture with stirring. The mixture is heated at a temperature of about 95° C. for 15 minutes. The mixture is then dried overnight at about 110° C. and calcined at about 400° C. for 3 hours. The resulting material is then suspended in 10 ml of distilled water and 0.62 g of Mn(NO₃)₂ is added to the mixture with stirring. The mixture is heated at a temperature of about 115° C. for 15 minutes. The mixture is then dried overnight at about 110° C. and calcined at about 400° C. for 3 hours.

Example 18 Preparation of Na₁₀MnW₅O₁₇/SiO₂ Nanowires

Nanowire material Na₁₀MnW₅O₁₇ (2.00 g), prepared as described in Example 16 above, is suspended in water, and about 221.20 g of a 40% by weight colloidal dispersion of SiO₂ (silica) is added while stirring. The mixture is heated at about 100° C. until near dryness. The mixture is then dried overnight at about 110° C. and heated under a stream of oxygen gas (i.e., calcined) at about 400° C. for 3 hours. The calcined product is cooled to room temperature and then ground to a 10-30 mesh size.

Example 19 Preparation of La₂O₃ Nanowires

Two identical syntheses were made in parallel. In each synthesis, 360 ml of 4 e12 pfu/ml solution of phage (SEQ ID NO: 3) were mixed in a 500 ml plastic bottle with 1.6 ml of 0.1 M LaCl3 aqueous solution and left incubating for at least 1 hour. After this incubation period, a slow multistep addition was conducted with 20 ml of 0.1 M LaCl3 solution and 40 ml of 0.3 M NH₄OH. This addition was conducted in 24 hours and 100 steps. The reaction mixture was left stirred for at least another hour at room temperature. After that time the suspension was centrifuged in order to separate the solid phase from the liquid phase. The precipitated material was then re-suspended in 25 ml of ethanol. The ethanol suspensions from the two identical syntheses were combined and centrifuged in order to remove un-reacted species. The gel-like product remaining was then dried for 15 hours at 65° C. in an oven and then calcined in a muffle oven in air (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 30min, ramp to 400° C. with 2° C./min rate, dwell for 240min, ramp to 550° C. with 2° C./min rate, dwell for 240min, cool to room temperature).

Example 20 Preparation of Mg/Na Doped La₂O₃ Nanowires

Two identical syntheses were made in parallel. In each synthesis, 360 ml of 4 e12 pfu solution of phage (SEQ ID NO: 3) were mixed in a 500 ml plastic bottle with 1.6 ml of 0.1 M LaCl₃ aqueous solution and left incubating for at least 1 hour. After this incubation period, a slow multistep addition was conducted with 20 ml of 0.1 M LaCl₃ solution and 40 ml of 0.3 M NH₄OH. This addition was conducted in 24 hours and 100 steps. The reaction mixture was left stirred for at least another hour at room temperature. After that time, the suspension was centrifuged in order to separate the solid phase from the liquid phase. The precipitated material was then resuspended in 25 ml of ethanol. The ethanol suspensions from the two identical syntheses were combined and centrifuged in order to remove un-reacted species. The gel-like product remaining was then dried for 15 hours at 65° C. in an oven.

The target doping level was 20 at % Mg and 5 at % Na at % refers to atomic percent). 182 mg of the dried product were suspended in 2.16 ml deionized water, 0.19 ml 1 M Mg(NO₃)₂ aqueous solution and 0.05 ml 1M NaNO₃ aqueous solution. The resulting slurry was stirred at room temperature for 1 hour, sonicated for 5 min, then dried at 120° C. in and oven until the powder was fully dried and finally calcined in a muffle oven in air (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 30min, ramp to 400° C. with 2° C./min rate, dwell for 60min, ramp to 550° C. with 2° C./min rate, dwell for 60min, ramp to 650° C. with 2° C./min rate, dwell for 60min, ramp to 750° C. with 2° C./min rate, dwell for 240min, cool to room temperature).

Example 21 Oxidative Coupling of Methane Catalyzed by Mg/Na Doped La₂O₃ Nanowires

50 mg of Mg/Na-doped La₂O₃ nanowires catalyst from example 20 were placed into a reactor tube (4 mm ID diameter quartz tube with a 0.5 mm ID capillary downstream), which was then tested in an Altamira Benchcat 203. The gas flows were held constant at 46 sccm methane and 54 sccm air, which correspond to a CH₄/O₂ ratio of 4 and a feed gas-hour space velocity (GHSV) of about 130000 h-1. The reactor temperature was varied from 400° C. to 450° C. in a 50° C. increment, from 450° C. to 550° C. in 25° C. increments and from 550° C. to 750° C. in 50° C. increments. The vent gases were analyzed with gas chromatography (GC) at each temperature level.

FIG. 22 shows the onset of OCM between 550° C. and 600° C. The C2 selectivity, methane conversion and C2 yield at 650° C. were 57%, 25% and 14%, respectively.

In another example, 50 mg of Mg/Na-doped La₂O₃ nanowires catalyst from example 20 were placed into a reactor tube (4 mm ID diameter quartz tube with a 0.5 mm ID capillary downstream), which was then tested in an Altamira Benchcat 203. The gas flows were held constant at 46 sccm methane and 54 sccm air, which correspond to a feed gas-hour space velocity (GHSV) of about 130000 h⁻¹. The CH₄/O₂ ratio was 5.5. The reactor temperature was varied from 400° C. to 450° C. in a 50° C. increment, from 450° C. to 550° C. in a 25° C. increments and from 550° C. to 750° C. in 50° C. increments. The vent gases were analyzed with gas chromatography (GC) at each temperature level.

FIG. 23 shows the onset of OCM between 550° C. and 600° C. The C2 selectivity, methane conversion and C2 yield at 650° C. were 62%, 20% and 12%, respectively.

Example 22 Nanowire Synthesis

Nanowires may be prepared by hydrothermal synthesis from metal hydroxide gels (made from metal salt+base). In some embodiments, this method is applicable to lanthanides, for example La, Nd, Pr, Sm, Eu, and lanthanide containing mixed oxides.

Alternatively, nanowires can be prepared by synthesis from metal hydroxide gel (made from metal salt+base) under reflux conditions. In some embodiments, this method is applicable to lanthanides, for example La, Nd, Pr, Sm, Eu, and lanthanide containing mixed oxides.

Alternatively, the gel can be aged at room temperature. Certain embodiments of this method are applicable for making magnesium hydroxychloride nanowires, which can be converted to magnesium hydroxide nanowires and eventually to MgO nanowires. In a related method, hydrothermal treatment of the gel instead of aging, is used.

Nanowires may also be prepared by polyethyleneglycol assisted hydrothermal synthesis. For example, Mn containing nanowires may be prepared according to this method using methods known to those skilled in the art. Alternatively, hydrothermal synthesis directly from the oxide can be used.

Example 23 Preparation of Nanowires

Nanostructured catalyst materials can be prepared by a variety of starting materials. In certain embodiments, the rare earth oxides are attractive starting materials since they can be obtained at high purity and are less expensive than the rare earth salt precursors that are typically used in preparative synthesis work. Methods for making rare earth oxide needles/nanowires and derivatives thereof are described below.

Method A: Lanthanide oxide starting material can be hydrothermally treated in the presence of ammonium halide to prepare rare earth oxide nanowires/needles. The preparation is a simple one-pot procedure with high yield. For example, one gram of lanthanum oxide was placed in 10 mL of distilled water. Ammonium chloride (0.98 g) was added to the water, the mixture was placed in an autoclave, and the autoclave was placed in a 160 C oven for 18 h. The autoclave was taken out of the oven, cooled, and the product was isolated by filtration. Micron and submicron needles were observed in the TEM images of the product. This method could also be used to prepare mixed metal oxides, metal oxyhalides, metal oxynitrates, and metal sulfates.

Method B: Mixed metal oxide materials can be prepared using a solid-state reaction of rare earth oxide or bismuth oxide in the presence of ammonium halide. The solid-state reaction is used to prepare the rare earth or bismuth oxyhalide. The metal oxyhalide is then placed in water at room temperature and the oxyhalide is slowly converted to metal oxide with nanowire/needle morphology. For example: lanthanum oxide, bismuth oxide, and ammonium chloride were ground and fired in a ceramic dish to make the mixed metal oxychloride. The metal oxychloride is then placed in water to form the mixed metal oxide needles.

Example 24 Preparation of MgO/Mn₂O₃ Core/Shell Nanowires

19.7 ml of concentrated solution of phages (e.g., SEQ ID NO: 3 at a concentration of ˜5E12 pfu/ml) were mixed in a 20 ml vial with 0.1 ml of 1 M LiOH aqueous solution and left incubating overnight (˜15h). 0.2 ml of 1 M MgCl₂ aqueous solution were then added using a pipette, and the mixture was mixed by gentle shaking. The reaction mixture was left incubating unstirred for 72 h. After the incubation time, the mixture was centrifuged and the supernatant decanted. The precipitated material was re-suspended in 5 ml of 0.001 M LiOH aqueous solution (pH=11), the mixture was centrifuged and the supernatant decanted.

19.8 ml of deionized water were added to the obtained Mg(OH)₂ nanowires. The mixture was left incubating for 1 h. After the incubation time, 0.2 ml of 1 M MnCl₂ aqueous solution were then added using a pipette and the mixture was mixed by gentle shaking. The reaction mixture was left incubating unstirred for 24 h. After the incubation time, the mixture was centrifuged and the supernatant decanted. The precipitated material was re-suspended in 3 ml of 0.001 M LiOH aqueous solution (pH=11), the mixture was centrifuged and the supernatant decanted. The precipitated material was finally re-suspended in 7 ml ethanol, the mixture was centrifuged and the supernatant decanted.

The obtained MnO(OH) coated Mg(OH)₂ nanowires were dried at 65° C. for 15 h in an oven. Finally, the dried product was calcined in a muffle furnace using a step recipe (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 60 min, ramp to 280° C. with 2° C./min rate, dwell for 60 min, ramp to 350° C. with 2° C./min rate, dwell for 60 min, ramp to 450° C. with 2° C./min rate, dwell for 60min, ramp to 550° C. with 2° C./min rate, dwell for 60min, cool to room temperature) to convert it to MgO/Mn₂O₃ core-shell nanowires.

The surface area of the nanowires was determined by BET (Brunauer, Emmett, Teller) measurement at 111.5 m²/g.

Example 25 Preparation of Mn₂O₃ Nanowires

3.96 ml of concentrated solution of phages (e.g., SEQ ID NO: 3 at a concentration of ˜5E12 pfu/ml) were mixed in a 8 ml vial with 0.04 ml of 1 M MnCl₂ aqueous solution and left incubating for 20 h. 0.02 ml of 1 M LiOH aqueous solution were then added using a pipette and the mixture was mixed by gentle shaking. The reaction mixture was left incubating unstirred for 72 h. After the incubation time, the mixture was centrifuged, and the supernatant was decanted. The precipitated material was re-suspended in 2 ml of 0.001 M LiOH aqueous solution (pH=11), the mixture was centrifuged and the supernatant decanted. The precipitated material was re-suspended in 2 ml ethanol, the mixture was centrifuged and the supernatant decanted. The obtained MnO(OH) nanowires were dried at 65° C. for 15 h in an oven. Finally, the dried product was calcined in a muffle furnace using a step recipe (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 60 min, ramp to 280° C. with 2° C./min rate, dwell for 60 min, ramp to 350° C. with 2° C./min rate, dwell for 60 min, ramp to 450 ° C. with 2° C./min rate, dwell for 60min, ramp to 550° C. with 2° C./min rate, dwell for 60min, cool to room temperature) to convert it to Mn₂O₃ nanowires.

Example 26 Preparation of V₂O₅ Nanowires

1.8 mg of V₂O₅ were dissolved in a 10 ml of a 2.5 wt % aqueous solution of HF. 1 ml of the V₂O₅/HF solution was mixed with 1 ml of concentrated solution of phages (e.g., SEQ ID NO: 3 at a concentration of ˜5E12 pfu/ml) in a 15 ml plastic centrifugation tube and left incubating for 2 h. 1 ml of a saturated solution of boric acid (supernatant of nominally 1 M boric acid aqueous solution) were then added using a pipette and the mixture was mixed by gentle shaking. The reaction mixture was left incubating unstirred for 170 h. After the incubation time, the mixture was centrifuged, and the supernatant was decanted. The precipitated material was suspended in 2 ml ethanol, the mixture was centrifuged and the supernatant decanted. The obtained V₂O₅ nanowires were characterized by TEM.

Example 27 Synthesis of MgO Nanowires

12.5 ml of a 4M MgCl₂ aqueous solution were heated to 70° C. on a hotplate. 0.1 g of MgO (from Aldrich) were then slowly added, over a span of at least 5 minutes, to the solution while it was vigorously stirred. The mixture was kept stirring at 70° C. for 3 h and then cooled down overnight (˜15 h) without stirring.

The obtained gel was transferred in a 25 ml hydrothermal bomb (Parr Bomb No. 4749). The hydrothermal bomb was then loaded in an oven at 120° C. and the solution was allowed to stand under autogenous pressure at 120° C. for 3 hours.

The product was centrifuged and the supernatant decanted. The precipitated product was suspended in about 50 ml ethanol and filtered over a 0.45 □m polypropylene hydrophilic filter using a Büchner funnel. Additional 200 ml ethanol were used to wash the product.

The obtained magnesium hydroxide chloride hydrate nanowires were suspended in 12 ml ethanol and 2.4 ml deionized water in a 20 ml vial. 1.6 ml of 5M NaOH aqueous solution were added and the vial was sealed with its cap. The mixture was then heated at 65° C. in an oven for 15 h.

The product was filtered over a 0.45 μm polypropylene hydrophilic filter using a Büchner funnel. About 250 ml ethanol were used to wash the product. The obtained Mg(OH)₂ nanowires were dried at 65° C. for 15 h in an oven. Finally, the dried product was calcined in a muffle furnace using a step recipe (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 60 min, ramp to 280° C. with 2° C./min rate, dwell for 60 min, ramp to 350° C. with 2° C./min rate, dwell for 60 min, ramp to 450° C. with 2° C./min rate, dwell for 60min, cool to room temperature) to convert it to MgO nanowires.

Example 28 Synthesis of Mg(OH)₂ Nanowires

6.8 g of MgCl₂.6H2O were dissolved in 5 ml deionized water in a 20 ml vial. 0.4 g of MgO (from Aldrich) were then slowly added to the solution while it was vigorously stirred. The mixture was kept stirring at room temperature until it completely jellified (˜2 h) and then it was left aging for 48 h without stirring.

The gel was transferred in a 50 ml centrifuge tube, which was then filled with deionized water and vigorously shaken until an homogenous suspension was obtained. The suspension was centrifuged and the supernatant decanted. The precipitated product was suspended in about 50 ml ethanol and filtered over a 0.45 □m polypropylene hydrophilic filter using a Büchner funnel. Additional 350 ml ethanol were used to wash the product.

The obtained magnesium hydroxide chloride hydrate nanowires were suspended in 24 ml ethanol in a 50 ml media bottle. The mixture was stirred for a few minutes, then 4.8 ml deionized water and 3.2 ml of 5M NaOH aqueous solution were added. The media bottle was sealed with its cap and the mixture was stirred for few more minutes. The mixture was then heated at 65° C. in an oven for 15 h.

The product was filtered over a 0.45 μm polypropylene hydrophilic filter using a Büchner funnel. About 400 ml ethanol were used to wash the product. The obtained Mg(OH)₂ nanowires were dried at 65° C. for 72 h in an oven and then additionally dried at 120° C. for 2 h in a vacuum oven. About 0.697 g of Mg(OH)₂ nanowires were obtained and the surface area of the nanowires was determined by BET (Brunauer, Emmett, Teller) measurement at 100.4 m²/g.

Example 29 Synthesis of MnO/Mn₂O₃ Core/Shell Nanowires

This example describes a method for coating the Mg(OH)₂ nanowires from example 28 with MnO(OH).

Three almost identical syntheses were conducted in parallel. In each synthesis, the Mg(OH)₂ nanowires, prepared using the method described in example 28 but without the drying steps, were mixed with 250 ml deionized water in a 500 ml plastic bottle and stirred for 20 minutes. 2.4 ml of a 1M MnCl₂ solution were added to the first synthesis, 6 ml of a 1M MnCl₂ solution were added to the second synthesis and 9.6 ml of a 1M MnCl₂ solution were added to the third synthesis. The mixtures were stirred for 2 hours at room temperature. After this incubation period, a slow multistep addition was conducted with 1.2 ml, 3 ml and 4.8 ml of 0.1 M LiOH solution for the first, second and third synthesis, respectively. This addition was conducted in 2 hours and 20 steps. The reaction mixture was left stirred overnight (˜15 h) at room temperature. After that time the suspensions were centrifuged in order to separate the solid phase from the liquid phase. The precipitated materials were then re-suspended in 50 ml of ethanol for each synthesis and filtered over a 0.45 μm polypropylene hydrophilic filter using a Büchner funnel. Additional 350 ml ethanol were used to wash each product of the three synthesis.

The obtained Mg(OH)₂/MnO(OH) core/shell nanowires were characterized by TEM before being dried at 65° C. for 72 h in an oven and then additionally dried at 120° C. for 2 h in a vacuum oven. The yield for the three syntheses was 0.675g, 0.653g and 0.688g, respectively. The surface area of the nanowires was determined by BET (Brunauer, Emmett, Teller) measurement at 94.6 m²/g, 108.8 m²/g and 108.7 m²/g, respectively.

The Mg(OH)₂/MnO(OH) core/shell nanowires can be converted into MgO/Mn₂O₃ nanowires by calcining them in a muffle furnace using a step recipe (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 60 min, ramp to 280° C. with 2° C./min rate, dwell for 60 min, ramp to 350° C. with 2° C./min rate, dwell for 60 min, ramp to 450° C. with 2° C./min rate, dwell for 60 min, ramp to 550° C. with 2° C./min rate, dwell for 60 min, cool to room temperature).

Example 30 Preparation of Nd₂O₃, Eu₂O₃ and Pr₂O₃ Nanowires

Three syntheses were made in parallel. In each synthesis, 10 ml of a 2.5 e12 pfu/ml solution of phage (SEQ ID NO: 14) were mixed in a 60 ml glass vial with 25 μl of 0.08M NdCl₃, EuCl₃ or PrCl₃ aqueous solutions, respectively and left incubating for at least 1 hour. After this incubation period, a slow multistep addition was conducted with 630 μl of 0.08M LaCl₃, EuCl₃ or PrCl₃ aqueous solutions, respectively and 500 μl of 0.3M NH4OH. This addition was conducted in 33 hours and 60 steps. The reaction mixtures were left stirred for at least another 10 hour at room temperature. After that time the suspensions were centrifuged in order to separate the solid phase from the liquid phase. The precipitated material was then re-suspended in 4 ml of ethanol. The ethanol suspensions were centrifuged in order to finish removing un-reacted species. The gel-like product remaining was then dried for 1 hours at 65° C. in an oven and then calcined in a muffle oven in air (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 30min, ramp to 500° C. with 2° C./min rate, dwell for 240 min, cool to room temperature). The obtained Nd(OH)₃, Eu(OH)₃ and Pr(OH)₃ nanowires were characterized by TEM before being dried.

Example 31 Preparation of Ce₂O₃/La₂O₃ Mixed Oxide Nanowires

In the synthesis, 15 ml of a 5 e12 pfu/ml solution of phage (SEQ ID NO: 3) were mixed in a 60 ml glass vial with 15 μl of 0.1M La(NO₃)₃ aqueous solution and left incubating for about 16 hour. After this incubation period, a slow multistep addition was conducted with 550 μl of 0.2M Ce(NO₃)₃ aqueous solution, 950 μl of 0.2M La(NO₃)₃ aqueous solution and 1500 μl of 0.4M NH₄OH. This addition was conducted in 39 hours and 60 steps. The reaction mixtures were left stirred for at least another 10 hours at room temperature. After that time the suspensions were centrifuged in order to separate the solid phase from the liquid phase. The precipitated material was then re-suspended in 4 ml of ethanol. The ethanol suspensions were centrifuged in order to finish removing un-reacted species. The gel-like product remaining was then dried for 1 hours at 65° C. in an oven and then calcined in a muffle oven in air (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 30min, ramp to 500° C. with 2° C./min rate, dwell for 120min, cool to room temperature).

Example 32 Synthesis of Pr₂O₃/La₂O₃ Mixed Oxide Nanowires

0.5 ml of 1M Pr(NO₃)₃ aqueous solution and 4.5 ml of 1M La(NO₃)₃ aqueous solution were mixed with 40 ml deionized water. Once well mixed, 5 ml of a 3M NH₄OH aqueous solution were quickly injected in the mixture. A precipitate immediately formed. The suspension was kept stirring for another 10 minutes then transferred to centrifuge tubes and centrifuged in order to separate the solid phase from the liquid phase. The precipitated material was then re-suspended in 35 ml of deionized water. The solid fraction was separated again by centrifugation and the washing step was repeated one more time. The gel-like product remaining was then dispersed in deionized water and the suspension volume adjusted to 20 ml. The suspension was then transferred to a hydrothermal bomb and placed in an oven at 120° C. for 2 hours. The solids obtained after hydrothermal treatment were then separated by centrifugation and washed once with 35 ml of deionized water. The washed hydrothermally treated powder was then dried at 120° C. for 16 hours. The surface area, determine by BET, of the dried powder was about 41 m²/g. Transmission electron microscopy was used to characterize the morphology of this sample further. The powder was constituted of large aspect ratio particles with about 30 nm wide by 0.5 to 2 μm length. The powder was calcined in three temperature steps at 200, 400 and 500° C. with 3° C. /min ramp and 2 hours of dwell time at each step. The surface area of the Pr2O₃/La₂O₃ mixed oxide nanowires was about 36 m²/g.

Example 33 Synthesis of MgO/Eu₂O₃ Core/Shell Nanowires

In this example, Mg(OH)₂ nanowires are used as a support to grow a shell of Eu(OH)₃. Mg(OH)₂ nanowires, prepared according to the methods described in example 28 (wet product, before being dried) were used to prepare a suspension in deionized water with a concentration of 3g/l of dried Mg(OH)₂. To 30 ml of the Mg(OH)₂ suspension, 3 ml of 0.1M Eu(NO₃)₃ aqueous solution and 3 ml of 0.3M NH₄OH aqueous solution were added in a slow multistep addition. This addition was conducted in 48 hours and 360 steps. The solids were then separated using centrifugation. The powder is washed with 30 ml DI water and centrifuged again. An aliquot is retrieved prior to calcination for transmission electron miscopy evaluation of the sample morphology. The sample is mainly constituted of high aspect ratio wires with a rough surface. The general morphology of the support is preserved and no separate phase is observed.

The remaining of the powder was dried at 120° C. for 3 hours and calcined in three steps at 200, 400 and 500° C. with 2 hours at each step and a ramp rate of 3° C. /min. The surface area, determined by BET, of the MgO/Eu₂O₃ core/shell nanowires is 209 m²/g.

Example 34 Synthesis of Y₂O₃/La₂O₃ Mixed Oxide Nanowires

0.5 ml of 1M Y(NO₃)₃ aqueous solution and 4.5 ml of 1M La(NO₃)₃ aqueous solution were mixed with 40 ml deionized water. Once well mixed, 5 ml of a 3M NH4OH aqueous solution was quickly injected in the mixture. A precipitate immediately forms. The suspension was kept stirring for another 10 minutes then transferred to centrifuge tubes and centrifuged in order to separate the solid phase from the liquid phase. The precipitated material was then re-suspended in 35 ml deionized water. The solid fraction was separated again by centrifugation and the washing step was repeated one more time. The gel-like product remaining was then dispersed in deionized water and the suspension volume adjusted to 20 ml. The suspension was then transferred to a hydrothermal bomb and placed in an oven at 120° C. for 2 hours. The solids obtained after hydrothermal treatment were then separated by centrifugation and washed once with 35 ml of deionized water. The washed hydrothermally treated powder was then dried at 120° C. for 16 hours. The surface area, determined by BET, of the dried powder is about 20 m2/g. Transmission electron microscopy was used to characterize the morphology of this sample further. The powder was constituted of large aspect ratio particles with about 20 to 40nm wide by 0.5 to 2 micron length. The Y₂O₃/La₂O₃ mixed oxide nanowires ware calcined in three temperature steps at 200, 400 and 500° C. with 3° C. /min ramp and 2 hours of dwell time at each step.

Example 35 Synthesis of La₂O₃ Nanowires

1g of La₂O₃ (13.1 mmol) and 0.92 g of NH₄Cl (18.6 mmol) were placed in a 25 ml stainless steel autoclave with a Teflon liner (Parr Bomb No. 4749). 10 ml deionized water were then added to the dry reactants. The autoclave was sealed and placed in a 160° C. oven for 12 h. After 12h, the autoclave was allowed to cool. The nanowires were washed several times with 10 mL of water to remove any excess NH₄Cl. The product was then dried in an oven for 15 hours at 65° C. in an oven and then calcined in a muffle oven in air (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 30min, ramp to 400° C. with 2° C./min rate, dwell for 240min, ramp to 550° C. with 2° C./min rate, dwell for 240min, cool to room temperature.)

Example 36 Synthesis of La₂O₃/Nd₂O₃ Mixed Oxide Nanowires

0.5g of La₂O₃ (1.5 mmol), 0.52g of Nd₂O₃ (1.5 mmol), and 0.325g of NH₄Cl (6 mmol) were ground together using a mortar and pestle. Once the dry reactants were well mixed, the ground powder was placed in a ceramic crucible and then the crucible was transferred to a tube furnace. The tube furnace atmosphere was flushed with nitrogen for 0.5 h. The reactants were then calcined under nitrogen (25° C.-450° C., 2° C. /min ramp, dwell 1 h; 450° C. -900° C.; 2° C./min ramp, 1 h hold, cool to room temperature.) The product (0.2 g) was placed in 10 mL of deionized water and stirred at room temperature for 24 h. The nanowires were then washed several times with deionized H₂O and dried in an oven for 15 hours at 65° C. in an oven and then calcined in a muffle oven in air (load in the furnace at room temperature, ramp to 100° C. with 2° C./min rate, dwell for 30 min, ramp to 400° C. with 2° C./min rate, dwell for 240min, ramp to 550° C. with 2° C./min rate, dwell for 240 min, cool to room temperature.)

Example 37 Oligomerization of Ethylene to Liquid Hydrocarbon Fuels with High Aromatics Content

0.1g of the zeolite ZSM-5 is loaded into a fixed bed micro-reactor and heated at 400° C. for 2 h under nitrogen to activate the catalyst. The OCM effluent, containing ethylene and ethane, is reacted over the catalyst at 400° C. at a flow rate of 50 mL/min and GSHV=3000-10000 mL/(g h). The reaction products are separated into liquid and gas components using a cold trap. The gas and liquid components are analyzed by gas chromatography. C5-C10 hydrocarbon liquid fractions, such as xylene and isomers thereof, represent 90% of the liquid product ratio while the C11-C15 hydrocarbon fraction represents the remaining 10% of the product ratio.

Example 38 Oligomerization of Ethylene to Liquid Hydrocarbon Fuels with High Olefins Content

0.1g of the zeolite ZSM-5 doped with nickel is loaded into a fixed bed micro-reactor and heated at 350° C. for 2 h under nitrogen to activate the catalyst. The OCM effluent, containing ethylene and ethane, is reacted over the catalyst at 250-400° C. temperature rage with GSHV=1000-10000 mL/(g h). The reaction products are separated into liquid and gas components using a cold trap. The gas and liquid components are analyzed by gas chromatography. C₄-C₁₀ olefin hydrocarbon liquid fractions, such as butene, hexane and octene represent ≥95% of the liquid product ratio while the C₁₂-C₁₈ hydrocarbon fraction represents the remaining 5% of the product ratio. Some trace amounts of odd numbered olefins are also possible in the product.

Example 39 Synthesis of MnWO₄ Nanowires

0.379g of Na₂WO₄ (0.001 mol) was dissolved in 5 mL of deionized water. 0.197g of MnCl₂.6H₂O (0.001 mol) was dissolved in 2 mL of deionized water. The two solutions were then mixed and a precipitate was observed immediately. The mixture was placed in a stainless steel autoclave with a Teflon liner (Parr Bomb No. 4749). 40 ml of deionized water was added to the reaction mixture and the pH was adjusted to 9.4 with NH₄OH. The autoclave was sealed and placed in a 120° C. oven. The reaction was left to react for 18h and then it was cooled to room temperature. The product was washed with deionized water and then dried in a 65° C. oven. The samples were calcined in a muffle oven in air (load in the furnace at room temperature, ramp to 400° C. with 5° C./min rate, dwell for 2 h, ramp to 850° C. with 5° C./min rate, dwell for 8 h, cool to room temperature).

Example 40 Preparation of Supported MnWO₄ Nanowire Catalysts

Supported MnWO₄ nanowires catalysts are prepared using the following general protocol. MnWO₄ nanowires are prepared using the method described in example 42. Manganese tungstate nanowires, support, and water are slurried for 6 h at room temperature. The manganese tungstate to support ratio is 2-10 wt %. The mixture is dried in a 65° C. oven and then calcined in a muffle oven in air: load in the furnace at room temperature, ramp to 400° C. with 5° C./min rate, dwell for 2 h, ramp to 850° C. with 5° C./min rate, dwell for 8 h, cool to room temperature. The following is a list of exemplary supports that may be used: SiO₂, Al₂O₃, SiO₂-Al₂O₃, ZrO₂, TiO₂, HfO₂, Silica-Aluminum Phosphate, and Aluminum Phosphate.

Example 41 OCM Catalyzed by La₂O₃ Nanowires

50 mg of La₂O₃ nanowires catalyst, prepared using the method described in example 19, were placed into a reactor tube (4 mm ID diameter quartz tube with a 0.5 mm ID capillary downstream), which was then tested in an Altamira Benchcat 203. The gas flows were held constant at 46 sccm methane and 54 sccm air, which correspond to a CH₄/O₂ ratio of 4 and a feed gas-hour space velocity (GHSV) of about 130000 h-1. The reactor temperature was varied from 400° C. to 500° C. in a 100° C. increment and from 500° C. to 850° C. in 50° C. increments. The vent gases were analyzed with gas chromatography (GC) at each temperature level.

FIG. 24 shows the onset of OCM between 500° C. and 550° C. The C2 selectivity, methane conversion and C2 yield at 650° C. were 54%, 27% and 14%, respectively.

The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure. 

1. A catalyst comprising an inorganic catalytic nanowire, the nanowire having a ratio of effective length to actual length of less than one and an aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the nanowire comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof, wherein the catalyst has a catalytic activity effective to catalyze the oxidative coupling of methane with a C₂ selectivity of greater than 30% at a temperature below 600° C.
 2. The catalyst of claim 1, wherein the one or more elements are in the form of oxides, hydroxides, oxyhydroxides, sulfates, carbonates, oxide carbonates, oxalates, phosphates, hydrogenphosphates, dihydrogenphosphates, oxyhalides, hydroxihalides, oxysulfates or combinations thereof.
 3. The catalyst of claim 2, wherein the one or more elements are in the form of oxides.
 4. The catalyst of claim 2, wherein the one or more elements are in the form of hydroxides.
 5. The catalyst of claim 1, wherein the nanowire comprises Mg, Ca, La, W, Mn, Mo, Nd, Sm, Eu, Pr, Zr or combinations thereof.
 6. The catalyst of claim 1, wherein the nanowire comprises MgO, CaO, La₂O₃, Na₂WO₄, Mn₂O₃, Mn₃O₄, Nd₂O₃, Sm₂O₃, Eu₂O₃, Pr₂O₃, Mg₆MnO₈, NaMnO₄, Na/Mn/W/O, MnWO₄ or combinations thereof.
 7. The catalyst of claim 1, wherein the nanowire further comprises one or more dopants comprising metal elements, semi-metal elements, non-metal elements or combinations thereof.
 8. The catalyst of claim 7, wherein the dopant comprises Li, Na, K, Mg, Ca, Ba, Sr, Eu, Sm, Co or Mn.
 9. The catalyst of claim 8, wherein the nanowire comprises Li/MgO, Ba/MgO, Sr/La₂O₃, Mg/Na/La₂O₃, Sr/Nd₂O₃, or Mn/Na₂WO₄.
 10. The catalyst of claim 7, wherein the atomic ratio of the one or more elements from Groups 1 through 7, lanthanides or actinides to the dopant ranges from 1:1 to 10,000:1.
 11. The catalyst of claim 1, wherein the nanowire comprises a combination of two or more compounds comprising the one or more elements.
 12. The catalyst of claim 11, wherein the nanowire comprises Mn₂O₃/Na₂WO₄, Mn₃O₄/Na₂WO₄ MnWO₄/Na₂WO₄/Mn₂O₃, MnWO₄/Na₂WO₄/Mn₃O₄ or NaMnO₄/MgO.
 13. The catalyst of claim 1, wherein the nanowire comprises a solid core.
 14. The catalyst of claim 1, wherein the nanowire comprises a hollow core.
 15. The catalyst of claim 1, wherein the nanowire has a diameter of between 7 nm and 200 nm as determined by TEM in bright field mode at 5 keV.
 16. The catalyst of claim 1, wherein the nanowire has an actual length of between 100 nm and 10 μm as determined by TEM in bright field mode at 5 keV.
 17. The catalyst of claim 1, wherein the nanowire has a ratio of effective length to actual length of less than 0.8.
 18. The catalyst of claim 1, wherein the nanowire has a bent morphology as determined by TEM in bright field mode at 5 keV.
 19. The catalyst of claim 1, wherein the powder x-ray diffraction pattern of the nanowire shows an average crystalline domain size of less than 50 nm.
 20. The catalyst of claim 1, wherein the catalyst further comprises a support material.
 21. The catalyst of claim 20, wherein the support material comprises an inorganic oxide, Al₂O₃, SiO₂, TiO₂, MgO, ZrO₂, HfO2, CaO, ZnO, LiAlO₂, MgAl2O₄, MnO, MnO₂, Mn₂O₄, Mn₃O₄, La₂O₃, activated carbon, silica gel, zeolites, activated clays, activated Al₂O₃, diatomaceous earth, magnesia, aluminosilicates, calcium aluminate, support nanowires or combinations thereof.
 22. The catalyst of claim 21, wherein the support material comprises SiO₂, ZrO₂, CaO, La₂O₃ or MgO.
 23. The catalyst of claim 1, wherein the nanowire comprises an inner core and an outer layer, the inner core and outer layer each independently comprising one or more elements selected from Groups 1 through 7, lanthanides and actinides.
 24. The catalyst of claim 1, wherein a methane conversion of the oxidative coupling of methane catalyzed by the nanowire is greater than at least 1.1 times the methane conversion obtained when the same reaction is performed under the same conditions but catalyzed by a catalyst prepared from bulk material having the same chemical composition as the nanowire.
 25. The catalyst of claim 1, wherein the C₂ selectivity of the oxidative coupling of methane catalyzed by the nanowire is greater than at least 1.1 times the C₂ selectivity obtained when the same reaction is performed under the same conditions but catalyzed by a catalyst prepared from bulk material having the same chemical composition as the nanowire.
 26. The catalyst of claim 1, wherein C2 yield of the oxidative coupling of methane catalyzed by the nanowire is greater than at least 1.1 times the C2 yield obtained when the same reaction is performed under the same conditions but catalyzed by a catalyst prepared from bulk material having the same chemical composition as the nanowire. 27-29. (canceled)
 30. The catalyst of claim 1, wherein the catalyst further comprises a biomolecule or modified or degraded forms thereof.
 31. A catalytic material comprising a plurality of inorganic catalytic nanowires, wherein the catalytic material has a catalytic activity effective to catalyze the oxidative coupling of methane with a C₂ selectivity of greater than 30% at a temperature below 600° C.
 32. The catalytic material of claim 31, wherein the plurality of inorganic catalytic nanowires has a surface area of between 0.001 and 1000 m²/g as measured by BET. 33-62. (canceled)
 63. A catalyst comprising an inorganic nanowire, the inorganic nanowire comprising one or more metal elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof and a dopant comprising a metal element, a semi-metal element, a non-metal element or combinations thereof, wherein the catalyst has a catalytic activity effective to catalyze the oxidative coupling of methane with a C₂ selectivity of greater than 30% at a temperature below 600° C.
 64. The catalyst of claim 63, wherein the nanowire comprises MgO, CaO, La₂O₃, Na₂WO₄, Mn₂O₃, Mn₃O₄, Nd₂O₃, Sm2O3, Eu₂O₃, Pr₂O₃, Mg₆MnO₈, NaMnO₄, MnWO4, Na/Mn/W/O or combinations thereof.
 65. The catalyst of claim 63, wherein the dopant comprises Li, Na, K, Mg, Ca, Ba, Sr, Eu, Sm, Co or Mn.
 66. The catalyst of claim 63, wherein the nanowire comprises Li/MgO, Ba/MgO, Sr/La₂O₃, Mg/Na/La₂O₃, Sr/Nd2O3, or Mn/Na₂WO₄. 67-113. (canceled)
 114. The catalytic material of claim 31, wherein the plurality of inorganic catalytic nanowires comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof in the form of oxides, hydroxides, oxyhydroxides, sulfates, carbonates, oxide carbonates, oxalates, phosphates, hydrogenphosphates, dihydrogenphosphates, oxyhalides, hydroxihalides, oxysulfates or combinations thereof.
 115. The catalytic material of claim 31, wherein the plurality of inorganic catalytic nanowires comprises Mg, Ca, La, W, Mn, Mo, Nd, Sm, Eu, Pr, Zr or combinations thereof.
 116. The catalytic material of claim 31, wherein the plurality of inorganic catalytic nanowires comprises MgO, CaO, La₂O₃, Na₂WO₄, Mn₂O₃, Mn₃O₄, Nd₂O₃, Sm₂O₂, Eu₂O₃, Pr₂O₃, Mg₆MnO₈, NaMnO₄, Na/Mn/W/O, MnWO₄ or combinations thereof.
 117. The catalytic material of claim 31, wherein the plurality of inorganic catalytic nanowires comprises one or more dopants comprising metal elements, semi-metal elements, non-metal elements or combinations thereof.
 118. The catalytic material of claim 117, wherein the dopant comprises Li, Na, K, Mg, Ca, Ba, Sr, Eu, Sm, Co or Mn.
 119. The catalytic material of claim 117, wherein the catalytic material comprises Li/MgO, Ba/MgO, Sr/La₂O₃, Mg/Na/La₂O₃, Sr/Nd₂O₃, or Mn/Na₂WO₄.
 120. The catalytic material of claim 114, wherein the plurality of inorganic catalytic nanowires comprises a combination of two or more compounds comprising the one or more elements.
 121. The catalytic material of claim 120, wherein the plurality of inorganic catalytic nanowires comprises Mn₂O₃/Na₂WO₄, Mn₃O₄/Na₂WO₄ MnWO₄/Na₂WO₄/Mn₂O₃, MnWO₄/Na₂WO₄/Mn₃O₄ or NaMnO₄/MgO.
 122. The catalytic material of claim 31, wherein the catalytic material further comprises a support material.
 123. The catalytic of claim 122, wherein the support material comprises an inorganic oxide, Al₂O₃, SiO₂, TiO₂, MgO, ZrO₂, HfO₂, CaO, ZnO, LiAlO₂, MgAl₂O₄, MnO, MnO₂, Mn₂O₄, Mn₃O₄, La₂O₃, activated carbon, silica gel, zeolites, activated clays, activated Al₂O₃, diatomaceous earth, magnesia, aluminosilicates, calcium aluminate, support nanowires or combinations thereof.
 124. The catalytic material of claim 31, wherein the plurality of inorganic catalytic nanowires comprises a plurality of polycrystalline inorganic nanowires. 